Wound therapy system with internal alternating orifice

ABSTRACT

A wound therapy system includes a dressing sealable over a wound and defining a wound space between the dressing and the wound, tubing fluidly communicable with the wound space, and a canister fluidly communicable with the tubing. The canister, the tubing, and the dressing define a sealed space that includes the wound space. The wound therapy system also includes a therapy unit coupled to the canister. The therapy unit includes a sensor configured to measure a pressure in the sealed space, a valve positioned between the sealed space and a surrounding environment and controllable between an open position and a closed position, and a control circuit. The control circuit is configured to control the valve to alternate between the open position and the closed position to allow airflow through the valve, receive measurements from the sensor, and determine a volume of the wound space based on the measurements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/802,034, filed on Feb. 6, 2019, which is incorporatedherein by reference in its entirety.

BACKGROUND

The present disclosure relates generally to a wound therapy system, andmore particularly to a wound therapy system that provides negativepressure wound therapy (NPWT). NPWT refers to the creation of negativepressure (relative to atmospheric pressure) at a wound to promotehealing of the wound. In a wound therapy system configured to provideNPWT, a dressing is typically sealed over a wound bed and placed influid communication with a pump operable to draw a negative pressure atthe wound bed (i.e., in a wound space between the wound bed and thedressing). Because the dressing is sealed over the wound bed, often fora period of multiple days, it may be difficult to ascertain and monitorthe progress of wound healing. One way to determine an amount of woundhealing is based on a change in the amount of volume between the woundbed and the dressing (i.e., as the wound heals into the volume tooccupy/consume part of the volume). Accordingly, systems and methods forvolume determination in a wound therapy system may be advantageous.

In some cases, NPWT may be provided in coordination with instillationtherapy and described as negative pressure and instillation woundtherapy (NPIWT). Instillation therapy refers to the provision ofinstillation fluid (e.g., saline, antibiotic fluid) to the wound. Onechallenge in instillation therapy may be determining how much fluid toprovide to the wound. It may be preferable to determine an amount offluid to provide based on a size of the wound and/or a volume ofavailable space adjacent the wound (i.e., between the dressing and thewound). Accordingly, systems and methods for volume determination in awound therapy system may facilitate instillation therapy.

SUMMARY

One implementation of the present disclosure is a wound therapy system.The wound therapy system includes a dressing sealable over a wound anddefining a wound space between the dressing and the wound, tubingcoupled to the dressing and fluidly communicable with the wound space,and a canister fluidly communicable with the tubing. The canister, thetubing, and the dressing define a sealed space that includes the woundspace. A therapy unit is coupled to the canister. The therapy unitincludes a pneumatic pump fluidly communicable with the sealed space, asensor configured to measure a pressure in the sealed space, a valvepositioned between the sealed space and a surrounding environment andcontrollable between an open position and a closed position, and acontrol circuit. The control circuit is configured to control thepneumatic pump to remove air from the sealed space to establish anegative pressure in the sealed space, control the valve to repeatedlyalternate between the open position and the closed position to allow acontrolled rate of airflow through the valve, receive measurements ofthe pressure in the sealed space from the sensor, and determine a volumeof the wound space based on the measurements of the pressure.

In some embodiments, the controlled rate of airflow is less than arestriction rate of a filter positioned between the valve and thecanister.

In some embodiments, valve includes a solenoid valve. The controlcircuit is configured to control the valve to repeatedly alternatebetween the open position and the closed position by providing a voltagepattern to the solenoid valve. The voltage pattern includes a stepfunction repeatedly stepping between approximately zero voltage and anon-zero voltage. The voltage pattern may remain at the non-zero voltagefor no more than a maximum continuous duration of approximately 500milliseconds.

In some embodiments, the voltage pattern includes a repeating pattern ofapproximately 400 milliseconds at a non-zero voltage, approximately 100milliseconds at approximately zero voltage, approximately 400milliseconds at the non-zero voltage, and approximately 100 millisecondsat approximately zero voltage. The voltage pattern includes a first setof two periods of the repeating pattern, approximately one second atapproximately zero voltage, and a second set of two periods of therepeating pattern. The voltage pattern may cause the solenoid valve toalternate between the open position and the closed position with aperiod of approximately 500 milliseconds.

In some embodiments, the control circuit is further configured tocustomize a customized wound therapy based on the volume of the woundspace and control the therapy unit to provide the customized woundtherapy. The customized wound therapy may include instillation therapy.

In some embodiments, the control circuit is configured to customize theinstillation therapy by determining an amount of instillation fluid tosupply to the wound space based on the volume of the wound space. Thewound therapy system may include instillation tubing coupled to thedressing and fluidly communicable with the wound space, a source of theinstillation fluid fluidly communicable with the instillation tubing,and an instillation pump controllable by the control circuit to providethe amount of the instillation fluid from the source to the wound space.

Another implementation of the present disclosure is a method of treatinga wound. The method includes establishing a sealed space defined by adressing, tubing, and a canister of a wound therapy system. The sealedspace includes a wound space defined by the dressing and the wound. Themethod includes removing, with a pneumatic pump, air from the sealedspace to establish a negative pressure in the sealed space and causing asolenoid valve to alternate between an open position and a closedposition. The solenoid valve allows an airflow from a surroundingenvironment to the sealed space in the open position and prevents theairflow from the surrounding environment to the sealed space in theclosed position. The method also includes measuring the pressure in thesealed space to generate pressure measurements, determining, based onthe pressure measurements, a volume of the wound space, customizing acustomized wound therapy based on the volume of the wound space, andproviding the customized wound therapy to the wound.

In some embodiments, customizing a customized wound therapy includesdetermining an amount of an instillation fluid to be supplied to thewound space based on the volume of the wound space. Providing thecustomized wound therapy to the wound includes controlling aninstillation pump to supply the amount of the instillation fluid to thewound space.

In some embodiments, causing the solenoid valve to alternate between theopen position and the closed position provides a controlled rate ofairflow from the surrounding environment to the sealed space. Thecontrolled rate of airflow is less than a restriction rate of a filterpositioned between the canister and the solenoid valve.

In some embodiments, causing the solenoid valve to alternate between theopen position and the closed position includes providing a voltagepattern to the solenoid valve. The voltage pattern may include a stepfunction repeatedly stepping between approximately zero voltage and anon-zero voltage. The voltage pattern may include a repeating pattern ofapproximately 400 milliseconds at a non-zero voltage, approximately 100milliseconds at approximately zero voltage, approximately 400milliseconds at the non-zero voltage, and approximately 100 millisecondsat approximately zero voltage.

In some embodiments, the voltage pattern includes a first set of twoperiods of the repeating pattern, approximately one second atapproximately zero voltage, and a second set of two periods of therepeating pattern. The non-zero voltage causes the solenoid valve to bein the open position. A positive pressure of approximately 5 mmHg isprovided to the sealed space during each 400 milliseconds at thenon-zero voltage.

Another implementation of the present disclosure is a wound therapysystem. The wound therapy system includes a dressing sealable over awound and defining a wound space between the dressing and the wound,first tubing coupled to the dressing and fluidly communicable with thewound space, a canister fluidly communicable with the first tubing,wherein the canister, the first tubing, and the dressing define a sealedspace that includes the wound space, a pneumatic pump fluidlycommunicable with the sealed space, a sensor configured to measure apressure in the sealed space, and a solenoid valve controllable betweenan open position and a closed position. The solenoid valve is configuredto allow air to flow from a surrounding environment to the sealed spacein the open position and prevent air from flowing from the surroundingenvironment to the sealed space in the closed position. The woundtherapy system also includes instillation tubing coupled to the dressingand fluidly communicable with the wound space and a source ofinstillation fluid, an instillation pump coupled to the instillationtubing and controllable to supply an amount of the instillation fluid tothe wound space, and a control circuit. The control circuit isconfigured to control the pneumatic pump to remove air from the sealedspace to establish a negative pressure in the sealed space and provide avoltage pattern to the solenoid valve. The voltage pattern causes thesolenoid valve to repeatedly alternate between the open position and theclosed position. The control circuit is also configured to receivemeasurements of the pressure from the sensor, determine a volume of thewound space based on the measurements of the pressure, determine theamount of the instillation fluid based on the volume of the wound space,and control the instillation pump to supply the amount of theinstillation fluid to the wound space.

In some embodiments, causing the solenoid valve to alternate between theopen position and the closed position allows a controlled rate ofairflow through the solenoid valve from the surrounding environment tothe sealed space.

In some embodiments, the solenoid valve is positioned to allow the airto enter one or more outer lumens of the first tubing. In someembodiments, a filter is positioned between the solenoid valve and theone or more outer lumens. Causing the solenoid valve to alternatebetween the open position and the closed position allows a controlledrate of airflow through the solenoid valve from the surroundingenvironment to the channel, and the controlled rate is less than arestriction rate of the filter.

In some embodiments, the instillation pump, the pneumatic pump, and thecontrol circuit are housed within a therapy unit. In some embodiments,the solenoid valve is positioned within the therapy unit. In someembodiments, the solenoid valve is positioned outside the therapy unitand coupled to the first tubing.

Another implementation of the present disclosure is a therapy unit. Thetherapy unit includes a pneumatic pump fluidly communicable with asealed space, a sensor configured to measure a pressure in the sealedspace, a valve positioned between the sealed space and a surroundingenvironment and controllable between an open position and a closedposition, and a control circuit. The control circuit is configured tocontrol the pneumatic pump to remove air from the sealed space toestablish a negative pressure in the sealed space, control the valve torepeatedly alternate between the open position and the closed positionto allow a controlled rate of airflow through the valve, receivemeasurements of the pressure in the sealed space from the sensor, anddetermine a volume of the sealed space based on the measurements of thepressure and the controlled rate, and provide a customized wound therapybased on the volume of the sealed space.

In some embodiments, the control circuit is configured to allow thecontrolled rate of airflow through the valve by controlling the valve tothe open position for no longer than a maximum continuous duration ofapproximately 500 milliseconds.

Another implementation of the present disclosure is a wound therapysystem. The wound therapy system includes a pneumatic pump fluidlycommunicable with a canister and tubing comprising a first lumen and asecond lumen. The first lumen is configured to facilitate the flow offluid from a dressing to the canister and the second lumen configured tofacilitate measurement of a pressure at the dressing. The wound therapysystem also includes a sensor configured to measure a pressure in thesecond lumen, a valve positioned between a second lumen and asurrounding environment and controllable between an open position and aclosed position, a filter positioned between the valve and the secondlumen, and a cap removeably coupleable to the tubing. The cap providesfluid communication between the first lumen and the second lumen whenthe cap is coupled to the tubing. The wound therapy system also includesa control circuit configured to, while the cap is coupled to the tubing,operate the pump to remove air from the canister, control the valve tothe open position, receive measurements of the pressure in the secondlumen from the sensor, and determine, based on the measurements of thepressure in the second lumen, a flow rate through the filter.

In some embodiments, the control circuit is configured to, while the capis removed from the tubing and the dressing is coupled to the tubing,determine a volume of a wound space based on the flow rate through thefilter and additional measurements of the pressure from the sensor. Insome embodiments, the control circuit is configured to provide acustomized wound therapy based on the volume of the wound space.

BRIEF DESCRIPTION OF THE FIGURES

Various objects, aspects, features, and advantages of the disclosurewill become more apparent and better understood by referring to thedetailed description taken in conjunction with the accompanyingdrawings, in which like reference characters identify correspondingelements throughout. In the drawings, like reference numbers generallyindicate identical, functionally similar, and/or structurally similarelements.

FIG. 1 is a partial block diagram of a negative pressure wound therapysystem including a therapy device coupled to a wound dressing viatubing, according to an exemplary embodiment.

FIG. 2 is a block diagram illustrating the negative pressure woundtherapy system of FIG. 1 in greater detail, according to an exemplaryembodiment.

FIG. 3 is a block diagram illustrating the negative pressure circuit,the removed fluid canister circuit and the wound site circuit of thenegative pressure wound therapy system of FIG. 1 in greater detail,according to an exemplary embodiment.

FIG. 4. is a block diagram illustrating a negative pressure woundtherapy system, according to an exemplary embodiment.

FIG. 5 is a flowchart of a method of using a negative pressure woundtherapy system, according to an exemplary embodiment.

FIG. 6A is a flowchart of method of instilling an initial quantity offluid to a wound site using the negative pressure wound therapy system,according to an exemplary embodiment.

FIG. 6B illustrates a negative pressure wound therapy system applied toa desired wound site to be treated, prior to the instillation of aninitial volume of fluid to the wound site according to an exemplaryembodiment.

FIG. 6C illustrates the negative pressure wound therapy system of FIG.6B following an application of a first negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 6D illustrates the negative pressure wound therapy system of FIG.6C during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 6C, according to an exemplary embodiment.

FIG. 6E illustrates the negative pressure wound therapy system of FIG.6B following an application of a second negative pressure to thenegative pressure wound therapy system, according to an exemplaryembodiment.

FIG. 6F illustrates the negative pressure wound therapy system of FIG.6E during venting of the negative pressure wound therapy systemfollowing the application of the second negative pressure as shown inFIG. 6E, according to an exemplary embodiment.

FIG. 6G illustrates the instillation of fluid to the wound site usingthe wound therapy system of FIG. 6B, according to an exemplaryembodiment.

FIG. 7 illustrates a negative pressure wound therapy system applied to awound site following an initial instillation of fluid to the wound site,according to an exemplary embodiment.

FIG. 8A is a flowchart of method of instilling an additional quantity offluid to a wound site using the negative pressure wound therapy systemof FIG. 7, according to an exemplary embodiment.

FIG. 8B illustrates the negative pressure wound therapy system of FIG. 7following an application of a first negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 8C illustrates the negative pressure wound therapy system of FIG.8B during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 8B, according to an exemplary embodiment.

FIG. 8D illustrates the negative pressure wound therapy system of FIG. 7following an application of a second negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 8E illustrates the negative pressure wound therapy system of FIG.8D during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 8D, according to an exemplary embodiment.

FIG. 9A is a flowchart of method of instilling an additional quantity offluid to a wound site to the negative pressure wound therapy system ofFIG. 7, according to an exemplary embodiment.

FIG. 9B illustrates the negative pressure wound therapy system of FIG. 7following an application of a first negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 9C illustrates the negative pressure wound therapy system of FIG.9B during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 9B, according to an exemplary embodiment.

FIG. 9D illustrates the negative pressure wound therapy system of FIG. 7following an application of a second negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 9E illustrates the negative pressure wound therapy system of FIG.9D during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 9D, according to an exemplary embodiment.

FIG. 10A is a flowchart of a method of determining whether sufficientdead space is present in a negative pressure wound therapy system,according to an exemplary embodiment.

FIG. 10B illustrates the negative pressure wound therapy system of FIG.7 following an application of a first negative pressure to the negativepressure wound therapy system, according to an exemplary embodiment.

FIG. 10C illustrates the negative pressure wound therapy system of FIG.10B during venting of the negative pressure wound therapy systemfollowing the application of the first negative pressure as shown inFIG. 10B, according to an exemplary embodiment.

FIG. 11 is a flowchart of a process for monitoring the healingprogression of the wound site over time, according to an exemplaryembodiment.

FIG. 12 is a flowchart of a method of instilling an initial quantity offluid to a wound site using the negative pressure wound therapy system,according to an exemplary embodiment.

FIG. 13 illustrates a negative pressure wound therapy system including atubeset module, according to an exemplary embodiment.

FIG. 14 illustrates a negative pressure wound therapy system including atubeset module, according to an exemplary embodiment.

FIG. 15 illustrates a negative pressure wound therapy system including atubeset module, according to an exemplary embodiment.

FIG. 16A is a block diagram of a negative pressure wound therapy systemincluding a tubeset module, according to an exemplary embodiment.

FIG. 16B illustrates the negative pressure wound therapy systemcomprising a tubeset module of FIG. 16A, according to an exemplaryembodiment.

FIG. 17 is a flowchart of a fully automated method of operating atubeset module, according to an exemplary embodiment.

FIG. 18 is a block diagram of a negative pressure and instillation woundtherapy (NPIWT) system, according to an exemplary embodiment.

FIG. 19 is a cross-sectional illustration of a solenoid valve of theNPIWT system of FIG. 18 in a closed position, according to an exemplaryembodiment.

FIG. 20 is a cross-sectional illustration of the solenoid valve of FIG.19 in an open position, according to an exemplary embodiment.

FIG. 21 is a cross-sectional illustration of tubing of the NPIWT systemof FIG. 18, according to an exemplary embodiment.

FIG. 22 is a flowchart of a process for managing blockages of the tubingof FIG. 21 using the solenoid valve of FIGS. 19-20, according to anexemplary embodiment.

FIG. 23 is a flowchart of a process for volume determination by theNPIWT system of FIG. 18, according to an exemplary embodiment.

FIG. 24 is a collection of graphs illustrating various aspects of theprocess of FIG. 23, according to an exemplary embodiment.

FIG. 25 is a block diagram of the NPIWT system of FIG. 18 with aremovable cap, according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE FIGURES Overview

Referring generally to FIGS. 1-17, a wound therapy system is shownaccording to various exemplary embodiments. The wound therapy system mayinclude a therapy device and a wound dressing. The therapy device mayinclude an instillation fluid canister, a removed fluid canister, avalve, a pneumatic pump, an instillation pump, a tubeset module and acontroller. The wound dressing can be applied to a patient's skinsurrounding a wound. The therapy device can be configured to deliverinstillation fluid to the wound and provide negative pressure woundtherapy (NPWT) by maintaining the wound at negative pressure. Componentsof the wound therapy device, the wound dressing, and the wound site forma negative pressure circuit.

The controller can be configured to operate the pneumatic pump, theinstillation pump, the tubeset module and/or other controllablecomponents of the therapy device. In some embodiments, the controllerestimates the volume of the wound based on a comparison of observeddynamic pressure responses to negative pressure being applied to theentirety of the negative pressure circuit and negative pressure beingapplied to a selected portion of the negative pressure circuit. Based onthe comparison of the observed dynamic responses, the controller may beconfigured to determine a quantity of instillation fluid to be deliveredto the wound site.

The tubeset module comprises one or more elements that are actuatable,controllable or which may otherwise be engaged by the controller, withthe selective communication of the controller with the tubeset modulebeing configured to allow the controller to, among other functions,effectuate and monitor various dynamic pressure responses in all ofand/or in parts of the negative pressure circuit as needed to estimatethe volume of the wound, determine a quantity of instillation fluid tobe delivered to the wound site and/or perform any other number offunctions that may be related to the use of the NPWT system 100.

According to some embodiments, the volume relative to the wound sitedetermined by the controller may relate to the dead space at the woundsite (i.e. the available space within a drape layer applied about thewound site into which instillation fluid may be delivered). In some suchembodiments, the controller may be configured to determine a quantity ofinstillation fluid to be delivered to the wound site based on apredetermined percentage of the calculated dead space volume at thewound site (e.g., 20%, 50%, 80%, etc.). The controller can then operatethe tubeset module and instillation pump to deliver the determinedvolume of instillation fluid to the wound. By basing the quantity ofinstillation fluid to be delivered to the wound site on a calculatedvolume of the dead space at the wound site, the negative pressure systemmay be configured to provide for more efficient and more precisedelivery of instillation fluid, which may reduce the risk of leakageresulting from over-delivery of instillation fluid and the risk ofineffective wound site treatment resulting from under-delivery ofinstillation fluid.

In some embodiments, the controller may additionally, or alternatively,measure and monitor volumes relative to the wound site at a plurality oftimes during wound treatment, with the controller determining healingprogression of the wound site based on changes in the measured volumerelative to the wound site over the course of NPWT treatment. Bymonitoring the healing progression of the wound site, the controller maybe configured to alert a user if the healing of the wound site is notprogressing as intended or expected. These and other features of thewound therapy system are described in detail below.

Wound Therapy System

Referring now to FIG. 1, a negative pressure wound therapy (NPWT) system100 is shown according to an exemplary embodiment. NPWT system 100 isshown to include a therapy device 102 fluidly connected to a wounddressing 112 via tubing 108 and 110. As will be described in more detailbelow, according to various embodiments a tubeset module 300 may beoperably connected to the tubing 108 and/or 110.

According to various embodiments, a wound dressing 112 may be placed onor within the wound site 114 and adhered or sealed to a patient's skin116 surrounding a wound site 114 using drape layer 117. Several examplesof wound dressings 112 which can be used in combination with NPWT system100 are described in detail in U.S. Pat. No. 7,651,484 granted Jan. 26,2010, U.S. Pat. No. 8,394,081 granted Mar. 12, 2013, and U.S. patentapplication Ser. No. 14/087,418 filed Nov. 22, 2013. The entiredisclosure of each of these patents and patent applications isincorporated by reference herein.

As illustrated by the block diagram of FIG. 2, in general the therapydevice 102 includes a pneumatic pump 120, an instillation pump 122, afilter 128, and a controller 118. Pneumatic pump 120 can be fluidlycoupled to removed fluid canister 106 (e.g., via conduit 136) and can beconfigured to draw a vacuum within removed fluid canister 106 by pumpingair out of removed fluid canister 106. In some embodiments, pneumaticpump 120 is configured to operate in both a forward direction and areverse direction. For example, pneumatic pump 120 can operate in theforward direction to pump air out of removed fluid canister 106 anddecrease the pressure within removed fluid canister 106. Pneumatic pump120 can operate in the reverse direction to pump air into removed fluidcanister 106 and increase the pressure within removed fluid canister106. Pneumatic pump 120 can be controlled by controller 118, describedin greater detail below.

Therapy device 102 can be configured to provide negative pressure woundtherapy by reducing the pressure at wound site 114. Therapy device 102can draw a vacuum at wound site 114 (relative to atmospheric pressure)by removing wound exudate, air, and other fluids from wound site 114.Wound exudate may include fluid that filters from a patient'scirculatory system into lesions or areas of inflammation. For example,wound exudate may include water and dissolved solutes such as blood,plasma proteins, white blood cells, platelets, and red blood cells.Other fluids 121 removed from wound site 114 may include instillationfluid 105 previously delivered to wound site 114. Instillation fluid 105can include, for example, a cleansing fluid, a prescribed fluid, amedicated fluid, an antibiotic fluid, or any other type of fluid whichcan be delivered to wound site 114 during wound treatment. Instillationfluid 105 may be held in an instillation fluid canister 104 andcontrollably dispensed to wound site 114 via tubing 108. In someembodiments, instillation fluid canister 104 is detachable from therapydevice 102 to allow removed fluid canister 106 to be refilled andreplaced as needed.

Instillation pump 122 can be fluidly coupled to instillation fluidcanister 104 via upstream instillation tubing 108 a and fluidly coupledto wound dressing 112 via downstream instillation tubing 108 b.Instillation pump 122 can be operated to deliver instillation fluid 105to wound dressing 112 and wound site 114 by pumping instillation fluid105 through upstream instillation tubing 108 a and downstreaminstillation tubing 108 b. Instillation pump 122 can be controlled bycontroller 118, described in greater detail below. According to someembodiments, an instillation tubing valve 109 valve configured to allowfor flow only in the direction from the instillation fluid canister 104to the wound site 114 (e.g. via a one-way valve or a via valveconfigured to be selectively switched by a user and/or by the controller118 to a closed position prior to the application of negative pressureto the wound site 114) may generally be provided at a location along aportion of the downstream instillation tubing 108 b. As will bedescribed in more detail below, according to various embodiments, theinstillation tubing valve 109 may be provided as part of the tubesetmodule 300.

Filter 128 can be positioned between removed fluid canister 106 andpneumatic pump 120 (e.g., along conduit 136) such that the air pumpedout of removed fluid canister 106 passes through filter 128. Filter 128can be configured to prevent liquid or solid particles from enteringconduit 136 and reaching pneumatic pump 120. Filter 128 may include, forexample, a bacterial filter that is hydrophobic and/or lipophilic suchthat aqueous and/or oily liquids will bead on the surface of filter 128.Pneumatic pump 120 can be configured to provide sufficient airflowthrough filter 128 that the pressure drop across filter 128 is notsubstantial (e.g., such that the pressure drop will not substantiallyinterfere with the application of negative pressure to wound site 114from therapy device 102).

Removed fluid canister 106 may be a component of therapy device 102configured to collect wound exudate and other fluids 121 removed fromwound site 114. In some embodiments, removed fluid canister 106 isdetachable from therapy device 102 to allow removed fluid canister 106to be emptied and replaced as needed. A lower portion of removed fluidcanister 106 may be filled with wound exudate and other fluids 107removed from wound site 114, whereas an upper portion of removed fluidcanister 106 may be filled with air. Therapy device 102 can beconfigured to draw a vacuum within removed fluid canister 106 by pumpingair out of removed fluid canister 106. The reduced pressure withinremoved fluid canister 106 can be translated to wound dressing 112 andwound site 114 via tubing 110.

As shown in FIG. 1, disposed along tubing 110 at a location between theremoved fluid canister 106 and the wound site 114 is a tubing valve 111configured to selectively permit and prevent fluid flow between theremoved fluid canister 106 and the wound site 114. The tubing valve 111may be defined by any number of different structures (e.g.spring-biased; duck-bill; clamp; check-valve, etc.) configured to allowfor the selective control of fluids through the tubing 110, and mayinclude valves that are configured to be selectively opened and/orclosed by a user, in response to a sensed stimulus (e.g. a predeterminedthreshold pressure), or by the controller 118. As will be described inmore detail below, according to various embodiments, the tubing valve111 may be provided as part of the tubeset module 300.

Referring to the block diagram of FIG. 3, when the tubing valve 111 isin an open, flow configuration, removed fluid canister 106, tubing 110(i.e. both upstream tubing portion 110 a and downstream tubing portion110 b), conduit 136 extending between pneumatic pump 120 and removedfluid canister 106, the portion of downstream instillation tubing 108 bextending between the drape layer 117 and instillation tubing valve 109,and wound site 114 are fluidly connected to define a negative pressurecircuit 200. Referring further to FIG. 3, when the tubing valve 111 isin a closed, no-flow configuration, the removed fluid canister 106,conduit 136 and an upstream tubing portion 110 a of the tubing 110extending between the removed fluid canister 106 and the tubing valve111 define a removed fluid canister circuit 202 that is fluidly isolatedfrom a wound site circuit 204 defined by the wound site 114, adownstream tubing portion 110 b of tubing 110 extending between thetubing valve 111, a portion of downstream instillation tubing 108 bextending between the drape layer 117 and instillation tubing valve 109,and the wound site 114. As will be discussed in more detail below, thevolumes of the tubing 110, conduit 136, and portion of downstreaminstillation tubing 108 b extending between the drape layer 117 andinstillation tubing valve 109 define known volumes which can be easilysubtracted from or otherwise factored into calculations of volume(s)relative to the wound site 114. Referring again to FIG. 1, according tosome embodiments, also provided along and operably fluidly connected totubing 110 at a location upstream of tubing valve 111 and downstream ofremoved fluid canister 106 is a calibrated leak system 113 defined by avent 113 a formed through an outer wall of the tubing 110, the vent 113a being selectively closeable by a vent valve 113 b. Also forming a partof calibrated leak system 113 may be a flow detector 113 c configured tomeasure airflow through the vent 113 a. As will be described in moredetail below, calibrated leak system 113 is configured to selectivelycontrol and measure airflow between tubing 110 and the ambientenvironment surrounding therapy device 102. According to variousembodiments, calibrated leak system 113 can be selectively opened toallow airflow into tubing 110 at a known, predetermined rate. As will bedescribed in more detail below, according to various embodiments,calibrated leak system 113 may be provided as part of the tubeset module300.

As will be described in more detail below, when both the vent valve 113b and the tubing valve 111 are closed, operation of the pneumatic pump120 may be configured to draw a vacuum in only the removed fluidcanister circuit 202 portion of the negative pressure circuit 200 (suchas, e.g., illustrated in FIG. 6E). When the vent valve 113 b is closedand the tubing valve 111 is open, operation of the pneumatic pump 120may be configured to draw a vacuum in the entirety of the negativepressure circuit 200 (such as, e.g., illustrated in FIG. 6C). When thevent valve 113 b is open and the tubing valve 111 is closed, airflowfrom the environment around therapy device 102 may enter through thevent 113 a of the calibrated leak system 113 and fill the vacuum withinthe removed fluid canister circuit 202 (such as, e.g., illustrated inFIG. 6F). As illustrated, e.g., by FIG. 6D, when both the vent valve 113b and the tubing valve 111 are open, airflow from the environment aroundtherapy device 102 may enter through the vent 113 a of the calibratedleak system 113 and fill the vacuum within the entirety of the negativepressure circuit 200. As will be understood, according to variousembodiments, the opening and/or closing of the vent valve 113 b and/ortubing valve 111 may be effectuated manually or automatically, e.g.,using tubeset module 300.

Although the calibrated leak system 113 has been disclosed as beingpositioned in-line with a portion of the tubing 110 extending betweenthe wound site 114 and the removed fluid canister 106, according to someembodiments, such as, e.g., illustrated in FIG. 4, the calibrated leaksystem 113 may be instead formed in-line with conduit 136. The operationof the calibrated leak system 113 of the embodiment of FIG. 4 is similarto the operation of the calibrated leak system 113 illustrated in FIG.1, with the calibrated leak system 113 of FIG. 4 being configured toprovide a path through which air from the ambient environment may flowinto and fill portions or the entirety of the negative pressure circuit200 following the creation of a vacuum within a portion or entirety ofthe negative pressure circuit 200. As will be understood, according tovarious embodiments, any of the methods or systems illustrated ordisclosed herein which incorporate a calibrated leak system 113embodiment as illustrated in FIG. 1 may be modified with a calibratedleak system 113 embodiment as illustrated in FIG. 4.

As illustrated by the block diagram of FIG. 2, according to variousembodiments, the controller 118 may be configured to operate variouscomponents of therapy device 102. In particular, as will be described inmore detail below, according to various embodiments, the controller 118may be configured to control the various components of the NPWT system100 to execute one or more volume determination procedures via which,e.g., a quantity of instillation fluid 105 to be delivered to the woundsite 114 may be determine, the healing progression of the wound site 114may be tracked, etc. According to various embodiments, the controller118 may be configured such that these procedures may be performed withminimal user intervention and/or input.

According to various embodiments, therapy device 102 may include avariety of sensors. For example, in some embodiments, therapy device 102may include pressure sensor 115 a and/or 115 b located in-line in theupstream tubing portion 110 a and/or downstream tubing portion 110 b,which are configured to measure pressure at the removed fluid canister106 and/or wound site 114. Pressure measurements recorded by pressuresensor(s) 115 a and/or 115 b can be communicated to controller 118.According to various embodiments, controller 118 may use the pressuremeasurements from pressure sensor(s) 115 a and/or 115 b as inputs tovarious pressure testing operations and control operations performed bycontroller 118. As will be described in more detail below, according tovarious embodiments, the pressure sensor(s) 115 a and/or 115 b may beprovided as part of the tubeset module 300.

In some embodiments, therapy device 102 includes a user interface 126.User interface 126 may include one or more buttons, dials, sliders,keys, or other input devices configured to receive input from a user.User interface 126 may also include one or more display devices (e.g.,LEDs, LCD displays, etc.), speakers, tactile feedback devices, or otheroutput devices configured to provide information to a user. Userinterface 126 can also display alerts generated by controller 118. Forexample, controller 118 can generate a “no canister” alert if removedfluid canister 106 is not detected.

In some embodiments, therapy device 102 includes a data communicationsinterface 124 (e.g., a USB port, a wireless transceiver, etc.)configured to receive and transmit data. Communications interface 124may include wired or wireless communications interfaces (e.g., jacks,antennas, transmitters, receivers, transceivers, wire terminals, etc.)for conducting data communications external systems or devices. Invarious embodiments, the communications may be direct (e.g., local wiredor wireless communications) or via a communications network (e.g., aWAN, the Internet, a cellular network, etc.). For example,communications interface 124 can include a USB port or an Ethernet cardand port for sending and receiving data via an Ethernet-basedcommunications link or network. In another example, communicationsinterface 124 can include a Wi-Fi transceiver for communicating via awireless communications network or cellular or mobile phonecommunications transceivers.

Methods of Use

Referring to FIG. 5, a flowchart of a method 500 of using NPWT system100 according to an exemplary embodiment is shown. As will be discussedin more detail with reference to FIGS. 6A-6G, initial set up of the NPWTsystem 100 and a delivery of an initial amount of instillation fluid 105to a wound site 114 being treated by the NPWT system 100 occurs at step502.

As shown at step 504, according to various embodiments, it may bedesirable to deliver additional instillation fluid 105 to the wound site114 following the instillation of an initial amount of instillationfluid 105 to the wound site 114. As will be understood, thedetermination at step 504 of when and if additional instillation fluid105 is to be delivered to the wound site 114 may be based on any numberof various factors, including e.g. elapsed time from a priorinstillation; type of wound site 114; desired course of wound site 114treatment; sensed conditions related to the wound site 114, etc., andmay be decided automatically by the controller 118, or may be based onuser input.

If it is determined at step 504 that additional fluid is to bedelivered, at step 506 the dead space 119 at the wound site 114 isdetermined according to any of the methods as will be described below.According to various embodiments (described in more detail below), atstep 506, the controller 118 may be configured to determine the deadspace 103 at the wound site 114 prior to such delivery of additionalinstillation fluid 105, irrespective of: whether the quantity ofinstillation fluid 105 previously instilled to the wound site 114 isknown; the presence of non-absorbed instillation fluid 105 and/or woundexudate in the space defined between the wound site 114 and the drapelayer 117; whether the volume of any contents 107 in the removed fluidcanister 106, the volume of the removed fluid canister 106 itself,and/or the volume of any contents 107 previously emptied from theremoved fluid canister 106 are known; whether the removed fluid canister106 has been replaced with a different-sized removed fluid canister 106during the course of the NPWT treatment; changes to theshape/size/volume of the wound site 114; etc.

At step 508, the quantity of additional instillation fluid 105 to bedelivered to the wound site 114 is calculated. According to variousembodiments, the quantity of additional instillation fluid 105 deliveredto the wound site 114 may be based on the volume of the dead spacedetermined at step 506. For example, in some embodiments, the controller118 may calculate the volume of instillation fluid 105 to be deliveredto wound site 114 by multiplying the volume if dead space determined atstep 506 by a fluid instillation factor. The fluid instillation factormay be equal to or less than one (i.e., between zero and one) such thatthe volume of instillation fluid 105 delivered to the wound site 114does not exceed the available space within the drape layer 117 (i.e.dead space), thereby minimizing the risk of inadvertent leakage from thewound dressing 112/drape layer 117. In some embodiments, the fluidinstillation factor is between approximately 0.2 and approximately 0.8.

In addition to being used to calculate instillation fluid 105 volumes,in some embodiments, the NPWT system 100 may be additionally, oralternatively, used to monitor and track the progress of healing of thewound site 114 over time. Accordingly, in some embodiments, method 500may optionally include the step 510 of estimating wound site 114 volume,and using the estimated volume to track healing progress of the woundsite 114, discussed in more detail with reference to FIG. 11 below.

In some embodiments, it may be desired to remove instillation fluid 105previously instilled to a wound site 114 from the wound site 114 at sometime following the delivery of the instillation fluid 105 to the woundsite 114. Accordingly, it may be advantageous to confirm, prior toinstilling instillation fluid 105 to the wound site 114, that the deadspace in the removed fluid canister 106 will be sufficient to receivethe removed instillation fluid 105 and/or any additional fluid 121 (e.g.wound exudate) from the wound site 114 prior to delivering theadditional instillation fluid 105 to the wound site 114. As such, method500 may optionally include step 512 at which the volume of additionalinstillation fluid 105 calculated at step 508 is compared to the deadspace of the removed fluid canister 106 (measured, e.g., during thedetermination of dead space at the wound site 114 at step 506), with analarm being presented to the user at step 514 if the instillation fluid105 to be delivered exceeds the dead space of the removed fluid canister106. If the instillation fluid 105 to be delivered does not exceed thedead space of the removed fluid canister 106 (or if step 512 is notincluded as part of method 500), the calculated instillation fluid 105is delivered to the wound site 114, with some or all of steps 504, 506,508, 510, 512, 514, 516 being repeated any number of additional timesover the course of the NPWT treatment.

Referring to FIG. 6A a flowchart detailing the steps of a method 600 foran initial set up of NPWT system 100 and for delivery of an initialamount of instillation fluid 105 to a wound site 114 entailed in step502 of the method 500 of FIG. 5 is shown according to one embodiment. Atstep 602, a NPWT system 100 (such as, e.g., illustrated in FIG. 1) isprovided, with the drape layer 117 and wound dressing 112 beingpositioned at the desired wound site 114 to be treated, as shown, e.g.,in FIG. 6B.

Once the set-up of the NPWT system 100 at step 502 is complete, thedetermination of the dead space 119 available at the wound site 114 intowhich instillation fluid 105 may be delivered may begin at step 604 withthe controller 118 operating the pneumatic pump 120 to establish a firstdesired negative pressure within the entirety of the negative pressurecircuit 200, such as, e.g., illustrated in FIG. 6C.

In embodiments in which the tubing valve 111 comprises a normally-closedpressure sensitive valve that is openable in response to an applied,predetermined threshold negative pressure, the first desired negativepressure generated by the controller 118 at step 604 may be equal to orgreater than the predetermined threshold pressure required to open thetubing valve 111, so as to ensure that the vacuum applied by thepneumatic pump 120 is applied across the entirety of the negativepressure circuit 200. In some embodiments, the threshold pressurerequired to open the tubing valve 111 may be a pressure of approximatelynegative 125 mmHg, with the controller 118 being configured to apply atstep 604 a first negative pressure that is equal to or greater thannegative 125 mmHg.

Alternatively, in embodiments in which the opening/closing of the tubingvalve 111 is controlled manually or in direct response to a signal fromthe controller 118 (using, e.g., a tubeset module 300 as describedbelow), the negative pressure delivered at step 604 may generallyinclude any desired range of negative pressures, with step 604 includingverification by the user and/or controller that the tubing valve 111 isin an open, flow orientation prior to the negative pressure beingapplied by the pneumatic pump 120. As illustrated, e.g., in FIG. 6C,according to various embodiments, the instillation tubing valve 109 andthe vent valve 113 b may be configured to be set to closedconfigurations during the application of negative pressure to thenegative pressure circuit 200.

As illustrated by FIG. 6D, at step 606, following the attainment of thedesired first negative pressure within the negative pressure circuit 200(as, e.g., measured and reported to the controller 118 by pressuresensor 115 a and/or pressure sensor 115 b), the operation of thepneumatic pump 120 is stopped, and the vent valve 113 b is opened toallow air from the ambient environment surrounding the therapy device102 to flow through the vent 113 a and into the negative pressurecircuit 200. According to various embodiments, the opening of the ventvalve 113 b at step 606 may be effectuated manually by a user or inresponse to instructions from the controller 118 being transmitted tothe tubeset module 300. In yet other embodiments, the calibrated leaksystem 113 may be formed without a vent valve 113 b (i.e. the vent 113 adefines a constant leak within the tubing 110), such that air from theambient environment surround the therapy device 102 will flow into thenegative pressure circuit 200 without requiring any user and/orcontroller 118 intervention.

As air from the ambient environment flows in to the negative pressurecircuit 200, parameters related to the flow of air through the vent 113a into the negative pressure circuit 200 are monitored (e.g. via flowdetector 113 c, pressure sensor 115 a, pressure sensor 115 b, etc.),with the measured parameters subsequently being used by the controller118 at step 612 to determine the volume of the negative pressure circuit200. According to various embodiments, the parameters related to theflow of air into the negative pressure circuit 200 may include, e.g.,the rate of flow of air into the negative pressure circuit 200 (asmeasured, e.g., by flow detector 113 c), the duration of time requiredfor pressure within the negative pressure circuit 200 to increase to apredetermined pressure (e.g. ambient pressure) following the opening ofthe vent 113 a and/or following operation of the pump 120 being ceased,the changing pressure (as, e.g., measured by pressure sensor 115 aand/or pressure sensor 115 b) within the negative pressure circuit 200as the pressure increases from the negative pressure applied at step 604to the predetermined pressure, etc.

Once the pressure within the negative pressure circuit 200 has increasedto a desired pressure and the measurement of the desired parameters hasbeen completed by the controller 118, the controller 118 may beconfigured operate pneumatic pump 120 to establish a second desirednegative pressure within the removed fluid canister circuit 202 portionof the negative pressure circuit 200 at step 608, such as, e.g.,illustrated in FIG. 6E. In embodiments in which the tubing valve 111comprises a normally-closed pressure sensitive valve that is openable inresponse to an applied, predetermined threshold negative pressure, thesecond desired negative pressure generated by the controller 118 at step608 may be less than the predetermined threshold pressure required toopen the tubing valve 111, so as to ensure that the vacuum applied bythe pneumatic pump 120 at step 608 is applied across only the removedfluid canister circuit 202 portion of the negative pressure circuit 200.For example, in some embodiments, the threshold negative pressurerequired to open the tubing valve 111 may be approximately negative 125mmHg, with the controller 118 being configured to apply a negativepressure at step 608 that is less than negative 125 mmHg, such as, e.g.,a pressure of approximately negative 50 mmHg.

Alternatively, in embodiments in which the opening/closing of the tubingvalve 111 is controlled manually or in direct response to a signal fromthe controller 118, the negative pressure delivered at step 608 maygenerally include any desired range of negative pressures, with step 608including verification by the user and/or controller that the tubingvalve 111 is in a closed, no-flow orientation prior to the negativepressure being applied by the pneumatic pump 120. As will be understood,in such embodiments, the second negative pressure applied by thecontroller 118 at step 608 to the removed fluid canister circuit 202 mayinclude a pressure that is equal to or different from the negativepressure that is applied by the controller 118 at step 604 to thenegative pressure circuit 200. As illustrated, e.g., in FIG. 6E,according to various embodiments, the instillation tubing valve 109 andthe vent valve 113 b may be configured to be set to closedconfigurations (either manually or automatically, e.g., using tubesetmodule 300) during the application of negative pressure to the removedfluid canister circuit 202 at step 608.

As illustrated by FIG. 6F, at step 610, following the attainment of thedesired second negative pressure within the removed fluid canistercircuit 202 (as, e.g., measured and reported to the controller 118 bypressure sensor 115 a and/or pressure sensor 115 b), the operation ofthe pneumatic pump 120 is stopped, and air from the ambient environmentsurrounding the therapy device 102 is allowed to flow through the vent113 a and into the removed fluid canister circuit 202. As air from theambient environment flows into the removed fluid canister circuit 202,parameters related to the flow of air through the vent 113 a and intothe removed fluid canister circuit 202 are monitored, with the measuredparameters subsequently being used by the controller 118 to calculatethe volume of the removed fluid canister circuit 202 at step 612.According to various embodiments, the parameters related to the flow ofair into removed fluid canister circuit 202 may include, e.g., the rateof flow of air into the removed fluid canister circuit 202 (as measured,e.g., by flow detector 113 c), the duration of time required forpressure within the removed fluid canister circuit 202 to increase to apredetermined pressure (e.g. ambient pressure) following the opening ofthe vent 113 a and/or ceasing operation or the pump 120 at step 610, thepressure (as, e.g., measured by pressure sensor 115 a and/or pressuresensor 115 b) within the removed fluid canister circuit 202 as thepressure increases from the negative pressure applied at step 608 to thepredetermined pressure; etc.

At step 612, the controller 118 may be configured to determine thevolumes of the removed fluid canister circuit 202 and the negativepressure circuit 200 based on the parameters measured at steps 606 and610. According to some embodiments, the controller 118 may base thesevolume calculations on stored relationships between various measuredparameter values and corresponding volumes. These relationships betweenmeasured parameter measurements and corresponding volumes that arestored by the controller 118 may include various functions, models,lookup table, etc., and may be based on pre-existing information inputand stored by the controller 118, or on information obtained andprocessed by the controller 118 during an optional, initial trainingprocedure conducted by the controller 118 prior to the use of the NPWTsystem 100 to treat wound site 114 (e.g. prior to the initiation ofmethod 500; as part of the initial setup and initial instillation ofinstillation fluid of step 502; etc.). One non-limiting examples ofembodiments of training procedures by which such relationships may begenerated by the controller 118 are outlined in related, co-pending U.S.Provisional Application 62/650,132, filed Apr. 17, 2018 and titled WOUNDTHERAPY SYSTEM WITH WOUND VOLUME ESTIMATION, the entire disclosure ofwhich is incorporated by reference herein.

Using the determined volumes of the removed fluid canister circuit 202and the negative pressure circuit 200, the controller 118 may determinethe volume of the dead space 119 at the wound site 114 (i.e. the portionof the interior space defined between the wound site 114 and the lowersurface of the drape layer 117 that is not occupied by the wounddressing 112 and/or any instillation fluid 105/other fluid) bysubtracting the volume of the removed fluid canister circuit 202 fromthe volume of the negative pressure circuit 200. According to variousembodiments, the determination of the volume of the dead space 119 atthe wound site 114 at step 614 may also include subtracting or otherwiseadjusting the calculated difference between the volumes of the removedfluid canister circuit 202 and the negative pressure circuit 200 toaccount for/factor in the known volumes of the downstream tubing portion110 b and the portion of the downstream instillation tubing 108 bextending between the drape layer 117 and the instillation tubing valve109 into the determination of the volume of the dead space 119 at thewound site 114.

At step 614, an initial quantity of instillation fluid 105 that is to bedelivered to the wound site 114 is calculated. According to variousembodiments, the calculated initial quantity of instillation fluid 105that is delivered to the wound site 114 may be based on the volume ofthe dead space 119 calculated by the controller 118 at step 612. Forexample, in some embodiments, the controller 118 may calculate theinitial volume of instillation fluid 105 to be delivered to the woundsite 114 by multiplying the volume of dead space 119 calculated at step612 by a fluid instillation factor. The fluid instillation factor may beequal to or less than one (i.e., between zero and one) such that thevolume of instillation fluid 105 delivered to the wound site 114 doesnot exceed the available space within the drape layer 117 (therebyminimizing inadvertent leakage from the wound dressing 112/drape layer117. In some embodiments, the fluid instillation factor is betweenapproximately 0.2 and approximately 0.8. However, it is contemplatedthat the fluid instillation factor can have any value in variousalternative embodiments.

As noted previously with reference to step 510, in addition to beingused to calculate a quantity of instillation fluid 105 to be deliveredduring any stage of treatment using NPWT system 100 and under any numberof different conditions (e.g. allowing for the calculation of additionalinstillation fluid 105 to be delivered at step 516 even if the removedfluid canister 106 has been emptied, or entirely replaced with adifferent sized removed fluid canister 106 during the course oftreatment), in some embodiments the NPWT system 100 may be additionally,or alternatively, used to monitor and track the progress of healing ofthe wound site 114 over time. Accordingly, in some embodiments, at step616, an initial baseline wound site 114 volume estimate may optionallybe determined (via, e.g., a method as described with regards to FIG. 11below) and stored by the controller 118, which may be used as areference point against which future wound site 114 volume estimates maybe compared to track healing progression of the wound site 114.

For reasons similar to those described with reference to step 512 of themethod 500 of FIG. 5, according to some embodiments, at step 618 theamount of initial instillation fluid 105 that is to be deliveredcalculated at step 614 may be compared to a determined dead space 103 ofthe removed fluid canister 106 to determine whether the dead spacewithin the removed fluid canister 106 will be sufficient to collect anyfluids 121 from the wound site 114 (including non-absorbed instillationfluid 105) following the delivery of instillation fluid 105 at step 516.As will be understood, in embodiments in which the NPWT system 100 hasnot been operated prior to the use of the NPWT system 100 at step 602,the volume of the removed fluid canister 106 should be empty, such thatthe dead space 103 of the removed fluid container 106 should be equal tothe volume of the removed fluid canister 106. If the volume of theremoved fluid canister 106 is not known and/or if removed fluid 107 ispresent in the removed fluid canister 106 at step 602, the dead space103 of the removed fluid container may be calculated by subtracting theknown volumes of conduit 136 and the upstream tubing portion 110 a fromthe volume of the removed fluid canister circuit 202 determined at step614. Similar to step 514, at step 620 an alarm may be presented to auser if the initial volume of instillation fluid 105 to be deliveredcalculated at step 614 exceeds the dead space 103 of the removed fluidcanister 106. Otherwise, if the volume of the initial instillation fluid105 to be delivered does not exceed the dead space 103 of the removedfluid canister 106, the calculated instillation fluid 105 is deliveredto the wound site 114 at step 622, as shown, e.g., in FIG. 6F.

Referring to FIG. 7, a NPWT system 100 according to one embodiment isshown at a point in time subsequent to a decision to instill additionalinstillation fluid 105 to the wound site 114 at step 504 of the method500 of FIG. 5, but prior to the determination of wound dead space at thewound site at step 506. As shown in FIG. 7, at the time immediatelypreceding the determination of dead space at the wound site 114 at step506, a quantity of fluid 121 (e.g. non-absorbed instillation fluid 105from a prior instillation, wound exudate, etc.) may be present in thespace between the drape layer 117 and the wound site 114, with theremaining space between the drape layer 117 and the wound site 114defining an initial dead space 119 a. As also shown in FIG. 7, accordingto some embodiments, an initial quantity of removed fluid 107 may bepresent in the removed fluid canister 106 at the time immediatelypreceding the start of step 506, with the remaining volume of theremoved fluid canister 106 being defined by an initial dead space 103 a.As will be understood, according to some embodiments, no fluid may bepresent at either the wound site 114 and/or in the removed fluidcanister 106 at the time immediately preceding step 506, in whichembodiments the quantities of each of the fluid 121 in the wound spaceand the removed fluid 107 in the removed fluid canister 106 would beequal to zero.

As noted above, a quantity of fluid 121 may be present at the wound site114 immediately prior to the initiation of step 506. According to someembodiments, it may not be desired and/or required to remove fluid 121from the wound site (e.g. non-absorbed instillation fluid 105 from priorinstillations, wound exudate, etc.) prior to the delivery of additionalinstillation fluid 105 to the wound site 114 at step 516 of the method500 of FIG. 5. Accordingly, in some embodiments of method 500, theadditional instillation fluid 105 instilled to the wound site at step516 may be delivered to the wound site 114 irrespective of any fluid 121that may be present at the wound site 114.

Referring to FIGS. 8A-8E, one embodiment of a method 800 of determiningan amount of dead space at a wound site 114 which may be used at step506 of the method 500 of FIG. 5 in embodiments in which fluid 121 fromthe wound site 114 is not removed from the wound site 114 prior toinstilling additional instillation fluid 105 is illustrated. Inparticular, according to the method 800 of FIGS. 8A-8E, as no fluid 121is displaced from the wound site 114 during the method 800 (i.e. step506), the final dead space into which the additional instillation fluid121 will be instilled will be the same initial dead space 119 a at thewound site that is present immediately prior to the initiation of step506 (i.e. the dead space 119 a shown in FIG. 7).

As shown by the flowchart in FIG. 8A, the method 800 of determining deadspace is substantially the same as the method 600 of calculating thedead space 119 upon initial instillation of instillation fluid 105 tothe wound site 114 at step 502 (which is discussed in more detail withreference to FIGS. 6A-6G). In particular, similar to steps 604 and 606,the method 800 of FIG. 8A also includes steps 802 and 804 (shown, e.g.,in FIGS. 8B and 8C, respectively) during which negative pressure isapplied to and removed from the negative pressure circuit 200. Similarto steps 608 and 610 of the method 600 of FIG. 6A, the method 800 ofFIG. 8 also includes steps 806 and 808 (shown, e.g., in FIGS. 8D and 8E,respectively) during which negative pressure is applied to and removedfrom the removed fluid canister circuit 202. Also similar to the method600 of FIG. 6A, in the method 800 of FIGS. 8A-8E, the application andsubsequent removal of negative pressure to the negative pressure circuit200 of steps 802 and 804 may be performed either prior to or after theapplication and subsequent removal of negative pressure to the removedfluid canister circuit 202 of steps 806 and 808.

As noted above, the method 800 of FIGS. 8A-8E may be performed insubstantially the same manner as the method 600 described withreferences to FIG. 6A above. However, whereas, as described above withreference to the method of FIGS. 6A-6E, according to variousembodiments, any range of negative pressures may generally be applied tothe negative pressure circuit 200 at step 604 of method 600, thenegative pressure applied to the negative pressure circuit 200 at step802 of the method 800 must be limited to negative pressures that willnot result in the fluid 121 at the wound site 114 being displaced intothe removed fluid canister 106. Following the completion of step 808,the controller 118 may be configured to calculate the volume of the deadspace 119 a at the wound site 114 (which corresponds to the maximumvolume of additional instillation fluid 105 that may be delivered towound site 114) at step 508 of method 500 of FIG. 5. More specificallyat step 508, after calculating the volumes of the removed fluid canistercircuit 202 and the negative pressure circuit 200 based on theparameters measured at steps 804 and 808 (in a manner similar to thatdescribed with reference to step 612 of the method 600 of FIGS. 6A-6G),the dead space 119 a at the wound site 114 may be calculated based onsubtracting the measured volume of the removed fluid canister circuit202 from the measured volume of the negative pressure circuit 200, withthe volume of the removed fluid canister circuit 202 of the method 800of FIGS. 8A-8E being defined by the dead space 103 a of the removedfluid canister 106, conduit 136 and upstream tubing portion 110 a; andthe volume of the negative pressure circuit 200 being defined by thevolume of the removed fluid canister circuit 202 (i.e. dead space 103 aof the removed fluid canister 106, conduit 136 and upstream tubingportion 110 a), the downstream tubing portion 110 b. dead space 119 a ofthe wound site 114 and the portion of downstream instillation tubing 108b extending between the drape layer 117 and instillation tubing valve109.

According to various embodiments, in embodiments of method 500 in whichthe determination of the volume of the dead space 119 a at the woundsite 114 at step 508 is based on measured parameters related to theremoved fluid canister circuit 202 and negative pressure circuit 200obtained using the method 800 of FIGS. 8A-8E, step 508 may also includesubtracting or otherwise adjusting the calculated difference between thevolumes of the removed fluid canister circuit 202 and the negativepressure circuit 200 to account for/factor in the known volumes of thedownstream tubing portion 110 b and the portion of the downstreaminstillation tubing 108 b extending between the drape layer 117 and theinstillation tubing valve 109 into the determination of the volume ofthe dead space 119 a at the wound site 114.

Although, as described above, in some embodiments of method 500,additional instillation fluid 105 may be delivered at step 516 withoutfirst removing any remaining fluid 121 at the wound site 114, accordingto other embodiments, it may be desirable to remove fluid 121 from thewound site 114 prior to the delivery of additional instillation fluid105.

Referring to FIGS. 9A-9E, one embodiment of a method 900 of determiningan amount of dead space at a wound site 114 which may be used at step506 of the method 500 of FIG. 5 in embodiments in which it is desired toremove fluid 121 from the wound site 114 prior to instilling additionalinstillation fluid 105 is illustrated. In particular, according to themethod 900 of FIGS. 9A-9E, any fluid 121 initially at the wound site 114immediately prior to step 506 (e.g. as shown in FIG. 7) is displacedfrom the wound site 114 during the method 900 (i.e. step 506), such thefinal dead space 119 b into which the additional instillation fluid 121will be instilled will be greater than the initial dead space 119 a atthe wound site that is present immediately prior to the initiation ofstep 506 by an amount generally corresponding to a volume of the fluid121 displaced from the wound site 114 to the removed fluid canister 106during the method 900.

As shown by the flowchart in FIG. 9A, the method 900 of determining deadspace is substantially the same as the method 600 of calculating thedead space 119 upon initial instillation of instillation fluid 105 tothe wound site 114 at step 502 (discussed in more detail with referenceto FIGS. 6A-6G). In particular, similar to steps 604 and 606, the method900 of FIG. 9A also includes steps 902 and 904 (shown, e.g., in FIGS. 9Band 9C, respectively) during which negative pressure is applied to andremoved from the negative pressure circuit 200. Similar to steps 608 and610 of the method 600 of FIG. 6A, the method 900 of FIG. 9 also includessteps 906 and 908 (shown, e.g., in FIGS. 9D and 9E, respectively) duringwhich negative pressure is applied to and removed from the removed fluidcanister circuit 202.

However, unlike the method 600 of FIG. 6A in which the application andsubsequent removal of negative pressure to the negative pressure circuit200 at steps 604 and 608 may be performed either prior to or after theapplication and subsequent removal of negative pressure to the removedfluid canister circuit 202 of steps 610 and 612, in the method 900 ofFIG. 9A, the application and subsequent removal of negative pressure tothe negative pressure circuit 200 at steps 902 and 904 is performedprior to the application and subsequent removal of negative pressure tothe removed fluid canister circuit 202 of steps 906 and 908.Additionally, whereas, as described above with reference to the methodof FIGS. 6A-6E, according to various embodiments, any range of negativepressures may generally be applied to the negative pressure circuit 200at step 604 of method 600, the negative pressure applied to the negativepressure circuit 200 at step 902 of the method 900 of FIG. 9A must besufficient to cause the displacement of fluid 121 from the wound site114 into the removed fluid canister 106.

Following the completion of step 908, the controller 118 may beconfigured to calculate the volume of the final dead space 119 b at thewound site 114 (which corresponds to the maximum volume of additionalinstillation fluid 105 that may be delivered to wound site 114) at step508 of method 500 of FIG. 5. More specifically at step 508, aftercalculating the volumes of the removed fluid canister circuit 202 andthe negative pressure circuit 200 based on the parameters measured atsteps 904 and 908 (in a manner similar to that described with referenceto step 612 of the method 600 of FIGS. 6A-6G), the final dead space 119b at the wound site 114 may be calculated based on subtracting themeasured volume of the removed fluid canister circuit 202 from themeasured volume of the negative pressure circuit 200, with the volume ofthe removed fluid canister circuit 202 of the method 800 of FIGS. 9A-9Ebeing defined by the final dead space 103 b of the removed fluidcanister 106 (with the final dead space 103 b of the removed fluidcanister 106 being generally equal to the difference between an initialdead space 103 a within the removed fluid canister 106 and the volume offluid 121 displaced into the removed fluid canister 106 from the woundsite 114 at step 802, as shown, e.g., in FIG. 9B), conduit 136 andupstream tubing portion 110 a; and the volume of the negative pressurecircuit 200 being defined by the volume of the removed fluid canistercircuit 202 (i.e. final dead space 103 b of the removed fluid canister106, conduit 136 and upstream tubing portion 110 a), the downstreamtubing portion 110 b. final dead space 119 b of the wound site 114 andthe portion of downstream instillation tubing 108 b extending betweenthe drape layer 117 and instillation tubing valve 109.

According to various embodiments, in embodiments of method 500 in whichthe determination of the volume of the dead space 119 at the wound site114 at step 508 is based on measured parameters related to the removedfluid canister circuit 202 and negative pressure circuit 200 obtainedusing the method 900 of FIGS. 9A-9E, step 508 may also includesubtracting or otherwise adjusting the calculated difference between thevolumes of the removed fluid canister circuit 202 and the negativepressure circuit 200 to account for/factor in the known volumes of thedownstream tubing portion 110 b and the portion of the downstreaminstillation tubing 108 b extending between the drape layer 117 and theinstillation tubing valve 109 into the determination of the volume ofthe dead space 119 a at the wound site 114.

In some embodiments of method 500 of FIG. 5 in which fluid 121 from thewound site 114 is removed prior to the instillation of additionalinstillation fluid 105 at step 516, it may be desirable to ensure thatthe initial dead space 103 a in the removed fluid canister 106immediately prior to beginning the step of determining dead space at thewound site at step 506 is sufficient to hold fluid 121 that will bedisplaced from the wound site 114 into the removed fluid canister duringstep 506, so as to avoid the risk of removed fluid canister 106overflow.

Accordingly, in some embodiments of method 500 in which fluid 121 fromthe wound site 114 is removed prior to the instillation of anyadditional instillation fluid 105 at step 516, the method of step 506 ofdetermining dead space at the wound site 114 (e.g., such as describedwith reference to the method 900 of FIGS. 9A-9E) may include determiningwhether there is sufficient dead space at the removed fluid canister 106to hold the fluid 121 from the wound site 114 that may be displaced intothe removed fluid canister 106 as part of the method of determining deadspace at the wound site 114.

Illustrated in FIGS. 10A-10C is one embodiment of such a method that maybe used to minimize the risk of overflow of the removed fluid canister106 during step 506 in which dead space at the wound site 114 is beingdetermined (e.g., via method 900 as described in FIGS. 9A-9E). At steps1002 and 1004 (shown in FIGS. 10B and 10C, respectively) negativepressure is applied to and removed from the removed fluid canistercircuit 202 to determine the initial dead space 103 a in the removedfluid canister 106 prior to beginning step 506 (e.g. as shown in FIG.7). In general, the steps 1002 and 1004 of the method 1000 of FIGS.10A-10E may be performed in a manner substantially similar to the mannerin which steps 608 and 610 of the method 600 of FIGS. 6A-6G areperformed. At step 1006, the volume of the removed fluid canistercircuit 202 is calculated based on the parameter measured at step 1004(in a manner similar to that described with reference to step 612 of themethod 600 of FIGS. 6A-6G). Once the volume of the removed fluidcanister circuit 202 has been calculated, the known volumes of theconduit 136 and the upstream tubing portion 110 a may be subtracted fromthe calculated removed fluid canister circuit 202 to determining thevolume of the initial dead space 103 a in the removed fluid canister 106(i.e. the maximum volume of fluid 121 displaced from the wound site 114that the removed fluid canister 106 may hold).

Once the volume of the initial dead space 103 a has been calculated atstep 1006, at step 1008, the controller 118 may be configured toestimate the volume of the fluid 121 at the wound site 114 at the timeimmediately preceding the determination of dead space at the wound site114 at step 506. The volume of the fluid 121 at the wound site 114 maybe based on any number of different factors and variables such as, e.g.,stored values of quantities of instillation fluid 105 previouslydelivered to the wound site 114, stored values of fluid 121 previouslyremoved from the wound site, elapsed time (e.g. from a priorinstillation, a prior removal of fluid 121, etc.), etc., with thecontroller 118 at step 1008 further being configured to compare thisestimated volume of fluid 121 to the initial dead space 103 a calculatedat step 1006, alerting the user to empty the removed fluid canister 106at step 1010 if the controller 118 determines that the estimated fluid121 volume exceeds the calculated initial dead space 103 a. If thecalculated initial dead space 103 a is sufficient to hold the estimatedvolume fluid 121 from the wound site 114, at step 1012 the controller118 may be configured to begin the step 506 of determining dead space atthe wound site 114, e.g., according to method 900 as described withreference to FIGS. 9A-9E.

As noted above, according to some embodiments of method 500, it may beadvantageous to monitor changes in the volume of the wound site 114 totrack the progress of the healing of the wound site 114 at an optionalstep 510.

In general, the volume of the wound site 114 is defined by the entiretyof the interior extending between the wound site 114 and the drape layer117 attached to the skin 116 about the wound site 114. At various pointsduring treatment using the NPWT system 100, located within and definingthe volume of the wound site may be any one of, and any combination of:the wound dressing 112, fluid 121, and/or dead space 119. As will beunderstood, unless the wound dressing 112 is replaced during treatment,the volume of the wound site 114 volume occupied by the wound dressing112 will generally remain unchanged over the course of treatment,whereas the portion of the wound site 114 volume occupied by the fluid121 and/or dead space 119 may change with time.

Referring to FIG. 11, a block diagram illustrating one embodiment of amethod 1100 of tracking wound site 114 healing progression which may beused at step 510 of the method 500 of FIG. 5 is illustrated. At step1102, an initial volume of the wound site 114 is estimated and recordedby the controller 118 at a point in time prior to an initialinstillation of instillation fluid 105 to the wound site 114, and mayserve as a baseline against which subsequent wound site 114 volumeestimates are compared to to track healing progress. According tovarious embodiments, estimation of the initial volume of the wound site114 at step 1102 may be performed according to (or as) step 616 ofmethod 600 described with reference to FIGS. 6A-6G.

At step 1104, the estimated volume of the wound site 114 is determinedand recorded at one or more additional times during treatment (e.g.,once per day) following the estimation of the initial wound site 114volume at step 1102, with the times at which such one or more wound site114 volumes are estimated and the values of the determined wound site114 volume being stored as data points within the memory of therapydevice 102 and/or presented to a user as an output of therapy device 102(e.g., via communications interface 124 or user interface 126). In someembodiments, the estimated wound volume can be plotted as a function oftime.

The additional wound site 114 volume estimates determined at one or moreadditional times over the course of treatment at step 1104 may beestimated according to any number of different processes. For example,according to some embodiments, the wound site 114 volume estimatesrecorded at step 1104 may be based on the final dead space volume at thewound site 114 calculated, e.g., at step 508 of method 500 and/or usingmethod 900 as described with reference to FIG. 5 and or 9A-9E,respectively.

As shown at step 510 of FIG. 5 and step 616 of FIG. 6A, according tosome embodiments, the wound site 114 volume estimates at steps 1102and/or steps 1104 may be performed in conjunction with method ofdelivering of instillation fluid 105 to the wound site 114. However, aswill be understood, according to other embodiments the determination ofand recording of some, all, or none of the wound site 114 volumeestimates at steps 1102 and/or steps 1104 may be performed independentof any delivery of instillation of instillation fluid 105 to the woundsite 114.

As additional wound site 114 volume estimates are obtained at steps1104, at step 1106, changes in the estimated wound site 114 volumes overtime may be used to determine healing progression of the wound site 114.For example, step 1106 may include comparing wound site 114 volumeestimates obtained at step 1104 to one or more previous estimates of thewound site 114 volume (obtained at either step 1104 or step 1102) toidentify a change in the wound site 114 volume. In some embodiments,step 1006 may additionally include determining a rate at which the woundsite 114 is healing based on the changes in the estimated wound site 114volume over time. In some embodiments, step 1106 may includeextrapolating or predicting a time at which wound site 114 will be fullyhealed based on the series of wound site 114 volume estimates stored bythe controller 118. For example, step 1106 may include predicting a timeat which the estimated wound site 114 volume will reach zero (or anotherthreshold value) based on the initial wound site 114 volume estimateobtained at step 1002 and the series of additional wound site 114 volumeestimates obtained at step 1004.

According to some embodiments, instead of, or in addition to, acalibrated leak system 113 being provided which is located upstream ofthe tubing valve 111, the NPWT system 100 may include a calibrated leaksystem 113 located downstream of the tubing valve 111. In general, suchembodiments in which a calibrated leak system 113 is located downstreamof the tubing valve 111 may operate in a manner substantially similar tothe various methods described with reference to FIGS. 1-11. However, incontrast to the step of monitoring the pressure decay within the removedfluid canister circuit 202, determining a volume of the removed fluidcanister circuit 202 based on the monitored pressure decay, andsubsequently using the determined volume of the removed fluid canistercircuit 202 to calculate wound site 114 volume, in the method 1200 ofFIG. 12, pressure decay is instead monitored within the wound sitecircuit 204, with the determined volume of the wound site circuit 204subsequently being used to calculate the dead space 103 in the removedfluid canister 106.

For example, referring to FIG. 12, a flowchart detailing the steps of amethod 1200 for an initial set up of NPWT system 100 and delivery of aninitial amount of instillation fluid 105 to a wound site 114 is shownaccording to one embodiment in which a calibrated leak system 113 of theNPWT system 100 is positioned downstream of the tubing valve 111. Ingeneral, steps 1202, 1204 and 1206 of the embodiment of the method 1200of FIG. 12 may be performed in a manner substantially similar to that asdescribed with reference to steps 602, 604 and 606 of the method 600 ofFIG. 6A.

At step 1208, the controller 118 is configured to initiate operation ofthe pump 120 to apply a second negative pressure (which may be equal toor different from the negative pressure applied by the controller 118 atstep 1204) to the negative pressure circuit 200. According to variousembodiments, the instillation tubing valve 109 and the vent valve 113 bmay be configured to be set to closed configurations during theapplication of negative pressure to the negative pressure circuit 200 atstep 1208. In embodiments in which a controller 118 controlled tubesetmodule 300 is used, the controller 118 may be configured to instruct thetubeset module 300 to effectuate the closing of the instillation tubingvalve 109 and/or the vent valve 113 b.

At step 1210, following the attainment of the desired second negativepressure within the negative pressure circuit 200 (as, e.g., measuredand reported to the controller 118 by pressure sensor 115 a and/orpressure sensor 115 b), the tubing valve 111 is closed so as to define awound site circuit 204, the operation of the pneumatic pump 120 isstopped, and air from the ambient environment surrounding the therapydevice 102 is allowed to flow through the vent 113 a of the and into thewound site circuit 204. As air from the ambient environment flows intothe wound site circuit 204, parameters related to the flow of airthrough the vent 113 a and into the wound site circuit 204 aremonitored, with the measured parameters subsequently being used by thecontroller 118 to calculate the volume of the wound site circuit 204 atstep 1212. According to various embodiments, the parameters related tothe flow of air into wound site circuit 204 may include, e.g., the rateof flow of air into the wound site circuit 204 (as measured, e.g., byflow detector 113 c), the duration of time required for pressure withinthe wound site circuit 204 to increase to a predetermined pressure (e.g.ambient pressure) following the opening of the vent 113 a and/or ceasingoperation or the pump 120 at step 1210, the pressure (as, e.g., measuredby pressure sensor 115 b) within the wound site circuit 204 as thepressure increases from the negative pressure applied at step 1208 tothe predetermined pressure; etc.

At step 1212, the controller 118 may be configured to determine thevolume of the wound site circuit 204 based on the parameters measuredduring step 1208. According to some embodiments, the controller 118 maybase this wound site circuit 204 volume calculation on storedrelationships between various measured parameter values andcorresponding volumes. These relationships between measured parametermeasurements and corresponding volumes that are stored by the controller118 may include various functions, models, lookup table, etc., and maybe based on pre-existing information input and stored by the controller118, or on information obtained and processed by the controller 118during an optional, initial training procedure conducted by thecontroller 118 prior to the use of the NPWT system 100 to treat woundsite 114 (e.g. prior to the initiation of method 500; as part of theinitial setup and initial instillation of instillation fluid of step502; etc.). One non-limiting examples of embodiments of trainingprocedures by which such relationships may be generated by thecontroller 118 are outlined in related, co-pending U.S. ProvisionalApplication 62/650,132, filed Apr. 17, 2018 and titled WOUND THERAPYSYSTEM WITH WOUND VOLUME ESTIMATION, the entire disclosure of which isincorporated by reference herein.

Using the determined volume of the wound site circuit 204, thecontroller 118 may determine the volume of the dead space 119 at thewound site 114 (i.e. the portion of the interior space defined betweenthe wound site 114 and the lower surface of the drape layer 117 that isnot occupied by the wound dressing 112 and/or any instillation fluid105/other fluid) by subtracting or otherwise adjusting the calculatedvolume of the wound site circuit 204 to account for/factor in the knownvolumes of the downstream tubing portion 110 b and the portion of thedownstream instillation tubing 108 b extending between the drape layer117 and the instillation tubing valve 109 into the determination of thevolume of the dead space 119 at the wound site 114.

At step 1214, an initial quantity of instillation fluid 105 that is tobe delivered to the wound site 114 is calculated. According to variousembodiments, the calculated initial quantity of instillation fluid 105that is delivered to the wound site 114 may be based on the volume ofthe dead space 119 calculated by the controller 118 at step 1212. Forexample, in some embodiments, the controller 118 may calculate theinitial volume of instillation fluid 105 to be delivered to the woundsite 114 by multiplying the volume of dead space 119 calculated at step1212 by a fluid instillation factor. The fluid instillation factor maybe equal to or less than one (i.e., between zero and one) such that thevolume of instillation fluid 105 delivered to the wound site 114 doesnot exceed the available space within the drape layer 117 (therebyminimizing inadvertent leakage from the wound dressing 112/drape layer117. In some embodiments, the fluid instillation factor is betweenapproximately 0.2 and approximately 0.8. However, it is contemplatedthat the fluid instillation factor can have any value in variousalternative embodiments.

As noted previously with reference to step 510, in addition to beingused to calculate a quantity of instillation fluid 105 to be deliveredduring any stage of treatment using NPWT system 100 and under any numberof different conditions (e.g. allowing for the calculation of additionalinstillation fluid 105 to be delivered at step 516 even if the removedfluid canister 106 has been emptied, or entirely replaced with adifferent sized removed fluid canister 106 during the course oftreatment), in some embodiments the NPWT system 100 may be additionally,or alternatively, used to monitor and track the progress of healing ofthe wound site 114 over time. Accordingly, in some embodiments, at step1216, an initial baseline wound site 114 volume estimate may optionallybe determined (via, e.g., a method as described with regards to FIG. 11)and stored by the controller 118, which may be used as a reference pointagainst which future wound site 114 volume estimates may be compared totrack healing progression of the wound site 114.

At step 1218 the dead space 103 of the removed fluid canister 106 may becalculated to determine whether the dead space within the removed fluidcanister 106 will be sufficient to collect any fluids 121 from the woundsite 114 (including non-absorbed instillation fluid 105) following thedelivery of instillation fluid 105 at step 516. As will be understood,in embodiments in which the NPWT system 100 has not been operated priorto the use of the NPWT system 100 at step 1202, the volume of theremoved fluid canister 106 should be empty, such that the dead space 103of the removed fluid container 106 should be equal to the volume of theremoved fluid canister 106.

The dead space 103 of the removed fluid container may be calculated bysubtracting the known volumes of conduit 136 and the upstream tubingportion 110 a from a volume of the removed fluid canister circuit 202determined by subtracting the volume of the wound site circuit 204calculated at step 1212 from a determined volume of the negativepressure circuit 200. As will be understood, the volume of the negativepressure circuit 200 may be determined in a manner similar to the methodvia which the volume of the wound site circuit 204 is determined at step1212.

Similar to step 514, at step 1220 an alarm may be presented to a user ifthe initial volume of instillation fluid 105 to be delivered calculatedat step 1214 exceeds the dead space 103 of the removed fluid canister106. Otherwise, if the volume of the initial instillation fluid 105 tobe delivered does not exceed the dead space 103 of the removed fluidcanister 106, the calculated instillation fluid 105 is delivered to thewound site 114 at step 1222.

As will be understood, in some NPWT system 100 embodiments in which acalibrated leak system 113 is provided both upstream and downstream ofthe tubing valve 111, the NPWT system 100 may be operated to estimatewound site 114 volume and/or estimate dead space 103 at the removedfluid canister 106 according to a method that is the same as or similarto the method 600 of FIG. 6A or a method that is the same as or similarto the method 1200 of FIG. 12.

In other embodiments of NPWT system 100 in which both an upstream anddownstream calibrated leak system 113 are provided, the NPWT system 100may be operated to estimate wound site 114 volume and/or estimate deadspace 103 at the removed fluid canister 106 according to a method thatis the same as or similar to the method 600 of FIG. 6A and a method thatis the same as or similar to the method 1200 of FIG. 12. For example,according to some embodiments, a modified method of operating a NPWTsystem 100 having both upstream and downstream calibrated leak systems113 may include the steps of: monitoring pressure decay within thenegative pressure circuit 200 (such as, e.g., described with referenceto step 606 of the method 600 of FIG. 6 and/or step 1206 of the method1200 of FIG. 12); monitoring pressure decay within the removed fluidcanister circuit 202 (such as, e.g., described with reference to step610 of the method 600 of FIG. 6); and monitoring pressure decay withinthe wound site circuit 204 (such as, e.g., described with reference tostep 1210 of the method 1200 of FIG. 12).

In such embodiments, the determination of wound site 114 volume based ondirect measurement (e.g. using the method 1200 of FIG. 12) may becompared to wound site 114 volume calculated based on indirectmeasurement (e.g. using the method 600 of FIG. 6A) and the determinationof dead space 103 at the removed fluid canister 106 based on directmeasurement (e.g. using the method 600 of FIG. 6A) may be compared todead space 103 volume calculated based on indirect measurement (e.g.using the method 1200 of FIG. 12). The controller 118 in suchembodiments may be configured to generate an alarm or alert in responseto a discrepancy between the direct and indirect measurements of woundsite 114 volume and/or dead space 103 at the removed fluid canister 106.By providing such redundancy to the wound site 114 and/or removed fluidcanister 106 dead space 103 calculations, such embodiments may beconfigured to allow the NPWT system 100 to provide more accurate andreliable results.

As will be understood, according to various embodiments, the controller118 may be programmed to allow the NPWT system 100 to determine volumerelative to the wound site 114 using any or all of the methods describedherein. Accordingly, while in some embodiments the controller 118 mayoptionally be preprogrammed to automatically determine a volume ofinstillation fluid 105 to be delivered according to a particular method(e.g. the method 900 embodiment illustrated in FIGS. 9A-9E), thecontroller 118 may optionally also allow a user to select any of theother modes of calculating a volume relative to the wound site 114 basedon whether the user desires to, e.g.: remove fluid 121 from the woundsite 114 prior to instillation of additional instillation fluid 105;verify sufficient dead space 103 a in the removed fluid canister 106prior to determining the dead space at the wound site 114; verifysufficient dead space 103 b in the removed fluid canister 106 prior tothe instillation of a calculated quantity of additional instillationfluid 105 to be delivered to the wound site 114; monitor changes in thewound site 114 volume to track healing progression; etc.

Tubeset Module

Although in some arrangements, some or all of the calibrated leak system113, tubing valve 111 and/or the instillation tubing valve 109, or otherNPWT system 100 components may be configured to be manuallyoperated/actuated/utilized by a user, as noted above, according tovarious embodiments, some or all of these components may alternativelybe configured to be operated/actuated/utilized by the controller 118,without requiring any user assistance to do so. In such a manner,implementation of the system for/method of determining a volume ofinstillation fluid to be delivered to a wound site, estimating a volumeof a wound, monitoring healing progression of a wound, and/or other useof the NPWT system 100 may be fully automated using the controller 118,allowing for easier use of the NPWT system 100.

By providing the NPWT system 100 with an automated manner via whichcontroller 118 may control or otherwise interact with one or more of thecalibrated leak system 113, tubing valve 111, instillation tubing valve109, and/or other component(s) of the NPWT system 100, the tubesetmodule 300 may increase the accuracy of the NPWT system 100. Forexample, in light of the ability of the controller 118 to utilize thetubeset module 300 to independently actuate (i.e. without userintervention) the operation of the calibrated leak system 113, thetubing valve 111 and/or the instillation tubing valve 109 elements, thecontroller 118 may be configured to increase the rate at which datarelated to instillation fluid volume estimation, wound site volumeestimation, wound site 114 healing progression monitoring, and/or otherfunctions of the NPWT system 100 is gathered. By increasing the datapoints used to provide such information, the reliability of theinformation provided by the controller 118 may thereby be increased.Similarly, the obviation or minimization of user involvement provided bythe tubeset module 300 may facilitate (and thereby increase thelikelihood of) the usage of a dual calibrated leak system 113arrangement as described with reference to FIG. 12 above, thus alsoincreasing the reliability of the NPWT system 100.

In general, the tubeset module 300 comprises a housing element 304containing a power source 301, a communications interface 302, and oneor more actuatable elements 303 configured to be controlled by thecontroller 118. In some embodiments, the tubeset module 300 mayoptionally also comprise one or more additional non-actuatable elements305, such as, e.g., pressure sensor 115 a and/or pressure sensor 115 b.According to embodiments in which calibrated leak system 113 is notdefined by a vent valve 113 b and only comprises a non-actuatable vent113 a, the non-actuatable element(s) 305 may comprise such a calibratedleak system 113 formed without a vent valve 113 b.

As will be understood, according to some embodiments, some or all of theactuatable elements 303 may be configured so as to be self-actuating. Insome such embodiments, the actuatable element 303 may comprise aninternal actuator that is in operably connected (via a wired, wireless,or any other type of connection) to the power source 301 and/orcommunications interface 302 of the tubeset module 300, via whichinstructions received from the controller 118 and/or power are relayedto the actuator of the actuatable element 303. In other suchembodiments, such self-actuation actuatable element 303 may individuallycomprise one or both of a power source and/or communications interface(in addition to the power source 301 and/or communications interface 302of the tubeset module). In such embodiments, the instructions from thecontroller 118 may be received directly by the communication interfaceof the actuatable element 303 from the controller, or may be receivedindirectly by the communication interface of the actuatable element 303from the communication interface 302 of the tubeset module 300. In otherembodiments, some or all of the actuatable elements 303 may beconfigured to be actuated by any number of different types of, orcombinations of known actuators that are contained by the housingelement 303, with the actuators of the housing element 303 beingconfigured to effectuate actuation of the one or more actuatableelements 303 in response to instructions received from the controller118.

The power source 301 may comprise any number of, and combination of,sources of energy that are configured to supply sufficient energy to thecommunications interface 302, actuatable element(s) 303 and/ornon-actuatable elements 305 contained by the housing element 304 asrequired for operation of the NPWT system 100. In some embodiments inwhich some or all of the tubeset module 300 is integrated into thetherapy device 102, the power provided by the power source 301 of thehousing element 304 may comprise a power source of the therapy device102.

The communications interface 302 may comprise any number of, andcombination of, wired and/or wireless connections via which the tubesetmodule 300 may receive communications (such as, e.g., actuation signals)from the controller 118. According to some embodiments, thecommunications interface 302 may optionally also be configured to sendinformation to and/or receive information from the controller 118, othertubeset module 300 housing elements 304 (such as, e.g., informationregarding the status of the one or more actuatable elements 303 and/ornon-actuatable elements 305 of the tubeset module 300), and/or othersources. In some embodiments in which some or all of the tubeset module300 is integrated into the therapy device 102, the communicationsinterface 302 of the housing element 304 may be defined by a portion ofa communications interface of the therapy device 102.

According to some arrangements, tubeset module 300 may be defined by asingle housing element 304, with each of actuatable elements 303 (e.g.upstream and/or downstream calibrated leak system 113, tubing valve 111and/or the instillation tubing valve 109, etc.) and/or non-actuatableelements 305 that are to be controlled/utilized by the controller 118forming a part of the single, integral housing element 304. In otherembodiments, the tubeset module 300 may be defined by a plurality ofseparate and distinct housing elements 304, with each housing element304 formed with one or more of the various actuatable elements 303and/or non-actuatable element 305 that are to be controlled/utilized bythe controller 118.

According to various arrangements, the one or more housing elements 304defining the tubeset module 300 may be provided as a separate, discrete,individual component of the NPWT system 100, which may subsequently beattached to or otherwise incorporated into one or more of the othercomponents of a new or existing NPWT system 100. In other arrangements,some or all of the one or more housing elements 304 defining the tubesetmodule 300 may be provided as an integrated part of one or more of theother components of the NPWT system 100.

For example, in some arrangements, some or the entirety of the tubesetmodule 300 may be integrated into the wound dressing 112, with theportion of the tubeset module 300 provided with the wound dressing 112being configured to be removed from the NPWT system 100 with the removalof the wound dressing 112. Upon removal of the integrated wound dressing112 /tubeset module 300, the entire wound dressing 112/tubeset module300 may be disposed of. Alternatively, the tubeset module 300 may beremoved from the wound dressing 112 prior to disposal of the wounddressing 112 and optionally reused with another wound dressing 112and/or other NPWT system 100 component.

In other arrangements, some or the entirety of the tubeset module 300may be integrated into the removed fluid canister 106, with the portionof the tubeset module 300 provided with the removed fluid canister 106being removed from the NPWT system 100 with the removal of the of theremoved fluid canister 106 from the NPWT system 100. In some suchembodiments, the tubeset module 300 may be monolithically formed withthe removed fluid canister 106, while in other embodiments; the tubesetmodule 300 may be non-integrally formed with the removed fluid canister106.

According to another arrangement, the tubeset module 300 may beconfigured to be integrated in-line with one or both of the tubing 108and/or 110. In such embodiments, attachment adapters 400 may be providedon one or both of the tubeset module 300 and/or tubing 108 and/or 110 tofacilitate a fluid tight attachment of the tubeset module 300 to thetubing 108 and/or 110. According to some embodiments, the attachmentadapters 400 may be provided on the tubeset module 300, with theattachment adapters 400 being configured to be able to form a fluidtight attachment directly with one or both of the tubing 108 and/or 110,allowing NPWT systems formed without a tubeset module 300 and/orcalibrated leak system 113, tubing valve 111 and/or the instillationtubing valve 109 to be retrofitted with a tubeset module 300 so as toprovide a NPWT system 100 as disclosed herein.

In some arrangements, some or the entirety of the tubeset module 300 maybe integrated into the housing of the therapy device 102. In suchembodiments, the efficiency of using the NPWT system 100 may beincreased, as by incorporating a tubeset module 300 including some orall of the calibrated leak system 113, tubing valve 111 and/or theinstillation tubing valve 109 into the housing of the therapy device102, the time to setup the NPWT system 100 may be reduced as compared tothe time that would otherwise be required to setup up a NPWT system 100in which some or all of the calibrated leak system 113, tubing valve 111and/or instillation tubing valve 109 were provided as separate anddiscrete components of the NPWT system 100. Additionally, byincorporating the tubeset module 300 into the housing of the therapydevice 102, a NPWT system 100 as described herein may be providedirrespective of the particular tubing, removed fluid canister, wounddressing, or other component(s) that are provided to define a NPWTsystem 100 for treatment of a wound site 114.

Referring to FIGS. 13-16, various embodiments of a tubeset module 300configured to allow for partially or fully automated control of the NPWTsystem 100 using the controller 118 are shown. As will be understood,although reference has been made to the controller 118 being provided aspart of the therapy device 102, it is to be understood that, accordingto various arrangements, the controller 118 may be provided separate andremote from the therapy device 102 and/or NPWT system 100 (e.g., by aremote medical provider). In such embodiments, the remotely providedcontroller 118 may be configured to communicate directly with thetubeset module 300 and/or indirectly with the tubeset module 300 via acommunications interface provided by the therapy device 102.

As illustrated by the NPWT system 100 embodiment of FIG. 13, in somearrangements, the tubeset module 300 is provided as a single, integratedhousing element 304 containing actuatable elements 303 comprising acalibrated leak system 113, a tubing valve 111 and an optionalinstillation tubing valve 109. According to some embodiments, one orboth of the tubing valve 111 and the optionally provided instillationtubing valve 109 may comprise the same or distinct clamps. As shown inFIG. 13, also contained within the housing element 304 is a power source301 configured to actuate the actuatable element 303 in response toinstructions being received from the controller 118 via thecommunications interface 302.

Although in the embodiment illustrated in FIG. 13 a single, integraltubeset module 300 is shown as being in-line with both tubing 108 andtubing 110, according to other arrangements (now shown) it is to beunderstood that a first housing element 304 comprising the calibratedleak system 113 and a tubing valve 111 may be provided in-line withtubing 110, while an optional, second housing element 304 comprisinginstillation tubing valve 109 may be provided in-line with tubing 110.

As illustrated by the NPWT system 100 of FIG. 13, in some embodiments,the tubeset module 300 may be formed integrally with upstream tubingportion 110 a and/or upstream instillation tubing 108 a. According tosome such embodiments, the upstream tubing portion 110 a and/or upstreaminstillation tubing 108 a with which the tubeset module 300 isintegrally formed may in turn be formed integrally with the therapydevice 102. In such embodiments, the tubeset module 300 is configured tobe removably attached to the downstream tubing portion 110 b and/ordownstream instillation tubing 108 b formed integral with the wounddressing 112, such that following use of the NPWT system 100 with afirst wound dressing 112, the therapy device 102 with integratedupstream tubing portion 110 a and/or upstream instillation tubing 108 aand tubeset module 300 may be reused with a new, second wound dressing112. In other embodiments, such as, e.g., illustrated by the NPWT system100 of FIG. 14, some or all of the tubeset module 300 may alternativelybe formed integrally with the wound dressing 112, with the tubesetmodule 300 being configured to be removed from the NPWT system 100 withthe removal of the wound dressing 112.

Referring to the NPWT system 100 of FIG. 15, according to someembodiments, the tubeset module 300 may comprise a first housing element304 containing a calibrated leak system 113 and an optional instillationtubing valve 109, pressure sensor 115 a and/or pressure sensor 119positioned in-line with the tubing 108 and/or 110. A second housingelement 304 comprising a tubing valve 111 may be spaced from the firsthousing element 304. As shown in FIG. 14, according to somearrangements, the second housing element 304 may be integrated into theremoved fluid canister 106. In other embodiments, the second housingelement 304 may alternatively be incorporated into the therapy device102, or may be provided at a second location in-line with the tubing110.

Referring to FIG. 16A, a block diagram of a NPWT system 100 accordingone embodiment is shown. As illustrated by the NPWT system 100 of FIG.16A, according to some embodiments, fluid communication between some orall of the negative pressure circuit 200 and the ambient environment maybe provided by a purge valve system 450 provided along the instillationtubing 108 as an alternative to, or in addition to, calibrated leak 113.According to various embodiments, the purge valve system 450 maycomprise a structure similar to that of calibrated leak system 113(including calibrated leak system 113 embodiments comprising anycombination of vent 113 a, vent valve 113 b and/or flow detector 113 ccomponents).

As also illustrated by FIG. 16A, in such NPWT system 100 embodiments,the tubing valve 111 and/or instillation tubing valve 109 may bereplaced by a valve assembly 460 that is fluidly attached to the tubing110 at a junction between the upstream tubing portion 110 a anddownstream tubing portion 110 b and that is attached to the instillationtubing assembly at a junction between the upstream tubing 108 a anddownstream tubing 108 b, and which is actuatable to a variety ofpositions. In a first position, the valve assembly 460 may permit fluidflow from the pneumatic pump 120 to the wound site 114 via tubing 110and from the instillation pump 104 to the wound site 114 viainstillation tubing 108. In a second position, the valve assembly 460may permit fluid flow from the pneumatic pump 120 to the wound site 114via tubing 110 while blocking fluid flow from the instillation pump 104to the wound site 114 via instillation tubing 108. In a third position,the valve assembly 460 may block fluid flow from the pneumatic pump 120to the wound site 114 via tubing 110 while permitting flow from theinstillation pump 104 to the wound site 114 via instillation tubing 108.In a fourth position, the valve assembly 460 may fluidly connect theupstream tubing portion 110 a with the upstream instillation tubing 108a, resulting in the isolation of the downstream tubing portion 110 b.the downstream tubing 108, and the wound dressing 112 from the remainedof the therapy device 102.

When in the first configuration, the valve assembly 460 defines anegative pressure circuit 200 is defined by the tubing 136, the fluidcanister 106, the tubing 110, the wound site 114 and the portion of theinstillation tubing extending between the wound site 114 and the purgevalve 450. When in the fourth configuration, the valve assembly 460defines a removed fluid canister circuit 202 is defined by the tubing136, the fluid canister 106, the upstream tubing portion 110 a, and theportion of the upstream tubing 108 a extending between the valveassembly 460 and the purge valve 450 and a wound site circuit 204defined by the downstream tubing portion 110 b. the wound site 114, andthe downstream tubing 108 b.

As will be understood, the valve assembly 460 and the purge valve 450 ofthe NPWT system 100 of FIG. 16A may be operated in a manner similar tothe operation of the tubing valve 111, calibrated leak, and/orinstillation tubing valve 109 as described with reference to any of themethods described herein for determining wound site volume, estimating avolume of fluid to be instilled, monitoring wound healing progression,or performing any other functions using the NPWT system 100.

Referring to FIG. 16B, a tubeset module 300 configured for used with aNPWT system 100 incorporating a purge valve 450 (such as, e.g. shown inFIG. 16A) is shown according to one embodiment. As illustrated by FIG.16B embodiments in which the purge valve 450 is provided as a discretecomponent of the therapy device 112 capable of being automaticallyactuated by the controller 118, the tubeset module 300 may comprise onlya single actuatable element 303, defined by valve assembly 460. As willbe understood, in other embodiments, (such as, e.g. where the purgevalve 450 provided as part of the therapy device is not automaticallyactuatable by the controller 118), the purge valve 450 may be providedas a part of a tubeset module 300 that is partially or entirelyintegrated into the therapy device 112.

Although in the NPWT system 100 embodiment illustrated in FIG. 16A thepure valve 450 is illustrated as being provided as part of the therapydevice 112, according to other embodiments, the purge valve 450 may bealternatively, or additionally, provided as a part of the upstreamtubing 108 a. In such embodiments, the purge valve 450 may accordinglybe provided as an actuatable element 303 of the tubeset module 300.

As will be understood, the controller 118 may be configured toeffectuate any number of different operations using the NPWT system 100based on the selective, fully automated actuation of/interaction withsome or all of the actuatable elements 303 and/or non-actuatableelements 305 of a tubeset module 300 according to any number ofdifferent methods and protocols. According to various embodiments, theorder and/or combination of instructions transmitted by controller 118to the tubeset module 300 and/or the information received by thecontroller 118 from the tubeset module 300 may be configured toautomatically operate the tubeset module 300 in a manner that allows thecontroller 118 to automatically effectuate one or more of the methods500, 600, 800, 900, 1000, 1100, 1200, etc. described herein.

Represented in FIG. 17 is one method 1700 via which the controller 118may utilize a tubeset module 300 containing actuatable elements 303comprising a tubing valve 111, instillation tubing valve 109, andcalibrated leak system 113 and non-actuatable element(s) 305 comprisingone or both of pressure sensor 115 a and/or pressure sensor 115 b toautomatically control the NPWT system 100 to determine dead space 119 ata wound site 114 according to a method such as, e.g., described withreference to the method 500 of FIG. 5 and the method 600 of FIG. 6A.

At step 1701, in response to the controller 118 being initiated todetermine dead space at a wound site 114 (such as, e.g., at step 506 ofthe method 500 of FIG. 5), the controller 118 may initiate communicationwith the tubeset module 300 to confirm that the instillation tubingvalve 109 and vent valve 113 b of the calibrated leak system 113 areclosed, and that the tubing valve 111 is opened. If the instillationtubing valve 109 and/or vent valve 113 b are open, the controller 118may instruct the tubeset module 300 to effectuate actuation of theinstillation tubing valve 109 and/or vent valve 113 b into a closedconfiguration. Similarly, if the tubing valve 111 is detected by thecontroller 118 as being closed, the controller 118 may transmitinstructions to the tubing valve 111 via the communications interface302 to actuate opening of the tubing valve 111.

Once the controller 118 has received, via the communications interface302, confirmation that the instillation tubing valve 109 and vent valve113 b are closed and the tubing valve 111 is open, the controller 118may be configured to initiate operation of the pneumatic pump 120 toapply negative pressure to the negative pressure circuit 200 (such as,e.g., described with reference to step 604 of the method 600 of FIG.6A). During operation of the pneumatic pump 120, the controller 118 atstep 1703 may be configured to receive from the pressure sensor 115 aand/or pressure sensor 115 b pressure readings corresponding to thepressure within the negative pressure circuit 200. As will beunderstood, the pressure readings received by the controller 118 at step1703 may be received continuously, at predetermined intervals, and/or inresponse to specific requests for pressure readings transmitted by thecontroller 118 to the tubeset module 300 via communications interface302.

In response to receiving pressure readings from the tubeset module 300indicative of the pressure within the negative pressure circuit 200having reached a threshold pressure, the controller 118 at step 1705 maybe configured to stop operation of the pneumatic pump 120 and transmitto the tubeset module 300 an actuation signal configured to cause theopening of the vent valve 113 b.

At step 1707, the controller 118 may be configured to receive from thepressure sensor 115 a and/or pressure sensor 115 b pressure readingscorresponding to pressure decay within the negative pressure circuit200, such as, e.g., described with reference to step 606 of FIG. 6A. Thepressure readings received by the controller 118 at step 1707 may bereceived continuously, at predetermined intervals, or in response tospecific requests for pressure readings transmitted by the controller118 to the tubeset module 300 via communications interface 302.

Once the controller 118 has received pressure readings from the tubesetmodule 300 indicative of the pressure within the negative pressurecircuit 200 having reach a threshold pressure (such as, e.g., ambientpressure), the controller 118 at step 1709 may be configured toeffectuate, using the tubeset module 300, the actuation of the closingof the tubing valve 111 and the vent valve 113 b in advance of theapplication of negative pressure to the resultant removed fluid canistercircuit 202 (such as, e.g., during step 608 of the method 600 of FIG.6A).

At step 1711, the controller 118 once again may be configured to receivepressure readings from the tubeset module 300. The pressure readingsreceived by the controller 118 at step 1711 may be receivedcontinuously, at predetermined intervals, or in response to specificrequests for pressure readings transmitted by the controller 118 to thetubeset module 300 via communications interface 302. In response toreceiving pressure readings from the tubeset module 300 indicative ofthe pressure within the removed fluid canister circuit 202 havingreached a threshold pressure, the controller 118 at step 1713 may beconfigured to stop operation of the pneumatic pump 120 and transmit tothe tubeset module 300 an actuation signal configured to cause theopening of the vent valve 113 b.

At step 1715, the controller 118 may be configured to receive from thepressure sensor 115 a pressure readings corresponding to pressure decaywithin the removed fluid canister circuit 202, such as, e.g., describedwith reference to step 610 of FIG. 6A. The pressure readings received bythe controller 118 at step 1715 may be received continuously, atpredetermined intervals, or in response to specific requests forpressure readings transmitted by the controller 118 to the tubesetmodule 300 via communications interface 302.

According to some embodiments, following step 1715, at step 1717, thecontroller 118 may be configured to actuate, using the tubeset module300, the opening of the instillation tubing valve 109, in advance of theinstillation of instillation fluid to the wound site 114 (such as, e.g.,described with reference to step 516 of the method 500 of FIG. 5 and/orstep 622 of the method 600 of FIG. 6A).

Wound Therapy System with Internal Alternating Orifice

Referring now to FIG. 18, an NPIWT system 2100 is shown, according to anexemplary embodiment. The NPIWT system 2100 includes a dressing 2102fluidly communicable with a canister 2104 via first tubing 2106 and atherapy unit 2108 coupled to the canister 2104. As shown in FIG. 18, theNPIWT system 2100 also includes an instillation fluid source 2110fluidly communicable with the dressing 2102 via the therapy unit 2108and second tubing 2112. The NPIWT system 2100 and components thereof maycorrespond to, may be implemented with, may be combined, and/or mayotherwise provide various features of the systems and methods describedabove with reference to FIGS. 1-17. It should be understood that thepresent disclosure contemplates various combinations of the embodimentsshown in the drawings.

The dressing 2102 is shown as applied to a wound bed 2114. The dressing2102 includes a drape 2116 sealed over the wound bed 2114 and a foamlayer 2118 positioned between the drape 2116 and the wound bed 2114. Invarious embodiments, the dressing 2102 may include various layers andfeatures. The drape 2116 may be made of a substantially air-impermeablematerial (e.g., a polyurethane-based material) and may include anadhesive border that allows the drape to be sealed to a patient's skinaround the wound bed 2114. The foam layer 2118 may include a manifoldinglayer that allows airflow therethrough and facilitates the distributionof negative pressure across the wound bed 2114. A wound space 2120 thatincludes the open volume (i.e., through which air may flow) in the foamlayer 2118 and otherwise situated between the drape 2116 and the woundbed 2114 is thereby established.

The first tubing 2106 extends from the dressing 2102 to the canister2104. A cross-section of the first tubing 2106 is shown in FIG. 21,according to an exemplary embodiment. As described in detail withreference to FIG. 21, the first tubing 2106 includes an inner lumen 2400and one or more outer lumens 2402. The inner lumen 2400 provides for theflow of fluid from the wound space 2120 into the canister 2104. The oneor more outer lumens 2402 are fluidly communicable with a pressuresensor 2124 to facilitate measurement of the pressure at the wound space2120. The one or more outer lumens 2402 are also fluidly communicablewith a valve 2126 as described below. It should be understood that,while described as inner and outer in the examples herein, anygeometrical arrangement of multiple lumens may be used in variousembodiments. A connection pad (e.g., low pressure interface) 2121 iscoupled to the drape 116 and facilitates connection of the first tubing106 to the dressing 2102.

The canister 2104 is configured to collect wound exudate (e.g., fluid,other debris) removed from the wound space 2120 via the first tubing2106. The canister 2104 is fluidly communicable with the wound space2120 via the first tubing 2106. The canister 2104, the first tubing2106, and the dressing 2102 thereby define a sealed space that includesthe wound space 120.

The therapy unit 2108 is coupled to the canister 2104 and includes apneumatic pump 2122 fluidly communicable with the sealed space, a sensor2124 configured and positioned to measure pressure in the sealed space,a valve 2126 positioned between the sealed space and an environment, auser interface 2128, and an instillation pump 2130 coupled to the secondtubing 2112. The therapy unit 2108 also includes a control circuit 2132communicably and operably coupled (e.g., capable of exchangingelectronic signals with) the pneumatic pump 2122, the sensor 2124, thevalve 2126, the user interface 2128, and the instillation pump 2130.

The pneumatic pump 2122 is controllable by the control circuit 2132 andoperable to pump (e.g., draw, remove) air from the canister 2104, thefirst tubing 2106, and the wound space 2120 (i.e., from the sealedspace). The pneumatic pump 2122 may thereby create a negative pressurein the sealed space relative to atmospheric pressure, for examplebetween 25 mmHg and 175 mmHg. The pneumatic pump 2122 may create apressure differential that causes fluid and debris to be drawn out ofthe wound space 2120, through the first tubing 2106, and into thecanister 2104.

The sensor 2124 is positioned and configured to measure the pressure inthe sealed space. As shown in FIG. 18, the pressure sensor 2124 ispositioned to measure pressure via one or more outer lumens 2402. Inother embodiments a sensor 2124 may be include to measure pressureelsewhere in the sealed space (e.g., in the canister 104). The sensor2124 provides pressure measurements to the control circuit 2132 (e.g.,digital values, analog signals). The control circuit 2132 may beconfigured to receive the pressure measurements from the sensor 2124 anduse the pressure measurements in a control loop to generate controlsignals for the pneumatic pump 2122 that cause the pneumatic pump 2122to maintain a desired pressure in the sealed space or provide a desiredpattern of pressure in the sealed space.

The user interface 2128 may include a display screen, a touch screen, aspeaker, a button, a switch, or any other element capable of providinginformation to a user or receiving input from a user. In someembodiments, the control circuit 2132 is configured to generate agraphical user interface and cause the graphical user interface to bedisplayed on the user interface 2128. The graphical user interface mayinclude various information about the NPIWT provided by the NPIWT system2100, for example relating to the pressure in the sealed space, anamount of instillation fluid to be provided, a schedule of negativepressure and instillation cycles, and/or a size of the wound space 2120.The user interface 2128 may allow a user to input commands and settingsrelating to the operation of the therapy unit 2108. The control circuit2132 may receive such inputs from the user interface 2128 and controlthe therapy unit 2108 in accordance with the inputs.

The instillation pump 2130 is configured to cause instillation fluid tobe transported from the instillation fluid source 2110 to the woundspace 2120 via second tubing 2112. The instillation pump 2130 may becontrollable by the control circuit 2132 to provide a desired amount ofthe instillation fluid to the wound space 2120, provide instillationfluid to the wound space 2120 at a desired rate, prevent instillationfluid from flowing to the wound space 2120, or otherwise control theflow of instillation fluid to the wound space 2120. The instillationpump may include a peristaltic pump or some other type of pump.

The valve 2126 is controllable between an open position and a closedposition. As shown in FIG. 18, the valve 2126 is located at an interiorof the therapy unit 2108 in pneumatic communication with a surroundingenvironment (e.g., ambient air) via a vent 2134 positioned along anexterior of the therapy unit 2108. The valve 2126 is also shown ascommunicable with the one or more outer lumens 2402 of the first tubing2106. A filter 2138 is located between the canister 2104 and the pump2122. When the valve 2126 is in the open position, air may flow betweenthe surrounding environment and the sealed space via the filter 2138.When the valve 2126 is in the closed position, air is prevented fromflowing therethrough. As shown in FIGS. 19-20 and described in detailwith reference thereto, the valve 2126 may be a solenoid valve. Invarious other embodiments, other types of valves may be included. Asdescribed in detail below, the valve 2126 may be controllable to allow asudden surge (“blast”) of air therethrough in a manner intended to cleara blockage in the one or more outer lumens 2402 of the first tubing2106. The valve 2126 may also be controllable to allow a controlled rateof airflow therethrough to facilitate determination of a volume of thewound space 2120.

The filter 2138 is configured to prevent contaminants from moving fromthe surrounding environment to the wound space 2120 via the valve 2126and the one or more outer lumens 2402. The filter 2138 thereby protectsthe wound 2114 from infection or other complications. The filter 2138restricts the rate of flow of air from the surrounding environment intothe sealed space through the filter 2138 (e.g., by creating a pressuredrop across the filter 2138 due to the filter media, contaminantstrapped in the filter media, etc.) to a maximum of a restriction rate ofthe filter 2138. The restriction rate may be difficult to ascertain, mayvary over time, or may be different in different instances of the filer2138 (i.e., differing across multiple therapy units 108).

In the embodiments shown, the restriction rate of the filter is lessthan a typical rate of airflow through the valve 2126 when the valve2126 is held in the open position for an extended amount of time (e.g.,500 milliseconds or greater). Accordingly, the difficulty in determiningthe restriction rate of the filter 2138 leads to a difficulty indetermining a rate of airflow into the sealed space when the valve 2126is held in the open position for an extended amount of time.

The control circuit 2132 is configured to control the operation of thetherapy device 2108. For example, as described in detail below, thecontrol circuit 2132 is configured to control the pneumatic pump 2112 toremove air from the sealed space to establish a negative pressure in thesealed space, control the valve 2126 to provide a controlled leak to thesealed space, receive pressure measurements from the sensor 2122,determine a volume of the wound space 2120 based on the pressuremeasurements, and customized a wound therapy based on the volume of thewound space 2120. In some embodiments, the control circuit 2132 is alsoconfigured to detect a potential blockage of a lumen of the first tubing2106, control the valve 2126 to the open position to allow a blast ofair therethrough, keep the valve 2126 open while the blast of air clearsthe blockage, and control the valve 2126 to return to the closedposition. These and other features of the control circuit 2132 aredescribed in detail below.

Referring now to FIGS. 19-20, cross-sectional views of the valve 2126are shown, according to exemplary embodiments. In the embodiments shown,the valve 2126 is a solenoid valve. FIG. 19 shows the valve 2126 in theclosed position and FIG. 20 shows the valve in the open position. Itshould be understood that FIGS. 19-20 show one of many possibleembodiments of the valve 2126.

The valve 2126 includes an inlet 2200 pneumatically communicable withthe surrounding environment via the vent 2134, an outlet 2202pneumatically communicable with the sealed space via channel 2136, asolenoid 2206, a plunger 2204 extending axially through the solenoid2206 and substantially centered in the solenoid, a stopper 2205 coupledto the plunger 2204, and a spring 2208 coupled to the plunger 2204. Thesolenoid 2206 has a positive lead 2210 and a negative lead 2212 shown asoperably coupled (e.g., conductively coupled) to the control circuit2132.

The solenoid 2206 includes a coil of wire through which the plunger 2204extends. When a current flows through the solenoid (e.g., when a voltagedifferential is applied across the solenoid 2206, a magnetic field iscreated in the solenoid 2206. The magnetic field is substantiallyaligned with a central axis of the solenoid. The plunger 2204 is made ofa magnetic material, such that the magnetic field causes movement of theplunger 2204 when voltage is applied across the solenoid 2206.

As shown in FIG. 19, a voltage of approximately zero volts is appliedacross the solenoid 2206. That is, the control circuit 2132 prevents avoltage difference between the positive lead 2210 and the negative lead2212. Accordingly, approximately zero current is created in the solenoid2206, and approximately zero magnetic field is created by the solenoid2206. The spring 2208 exerts a force on the plunger 2204 that holds thestopper 2205 adjacent the inlet 2200. The stopper 2205 prevents air fromentering the valve 2206 via the inlet 2200. Airflow from the vent 2134to the channel 2136 is thereby prevented (i.e., the valve 126 is in theclosed position).

As shown in FIG. 20, a non-zero voltage is applied across the solenoid(e.g., approximately 5 volts). That is, the control circuit 2132provides a control signal to the valve 2126 by creating a voltagedifferential between the positive lead 2210 and the negative lead 2212of the solenoid 2206. It should be understood that, in variousembodiments, various values of the non-zero voltage may be required tooperate the valve 2126. When the control circuit 2132 provides anon-zero voltage to the valve 2126 (i.e., across the solenoid 2206), amagnetic field is created that causes the plunger 2204 to compress thespring 2208 and move the stopper 2205 away from the inlet 2200. Air maythen flow from the vent 2134 through the valve 2126 to the sealed space(i.e., the valve 2126 is in the open position).

When the non-zero voltage is removed (i.e., when the voltagedifferential between the positive lead 2210 and the negative lead 2212is brought to approximately zero), the magnetic field goes to zero andthe spring 2208 forces the plunger 2204 and stopper 2205 back to theclosed position shown in FIG. 19. Thus, the valve 2126 may be controlledto repeatedly alternate between the closed position shown in FIG. 19 andthe open position shown in FIG. 20 by alternating between anapproximately zero voltage and an approximately non-zero voltage.Example voltage patterns for controlling the valve 2126 to provide acontrolled rate of airflow therethrough are described in detail below.

Referring now to FIG. 21, a cross-sectional view of the first tubing2106 is shown, according to an exemplary embodiment. In the embodimentshown, the first tubing 2106 includes an inner lumen 2400 and four outerlumens 2402. That is, the first tubing 2106 is shown to include fiveseparate lumens (e.g., channels, bores, pathways) through which air,fluid, and/or other debris may flow. Preferably, fluid and debris flowsprimarily through the inner lumen 2400, while air flows through theouter lumens 2402. At or near the canister 2104, the path of the outerlumens 2402 is separated from the path of the inner lumen 2400 as shownin FIG. 18. The inner lumen 2400 is connected to the inner volume of thecanister to allow fluid and debris from the wound space 2120 to becollected in the canister. The outer lumens 2402 are connected to thesensor 2124 to facilitate the measurement and monitoring of pressure atthe wound space.

The connection pad 2121 may include groves and other physical featuresconfigured to direct fluid and debris towards the inner lumen 2400 andaway from the outer lumens 2402. However, fluid and debris mayoccasionally reach one or more of the outer lumens 2402 and cause ablockage of the one or more of the outer lumens 2402. A blockage of theinner lumen 2400 may also occur. As described below with reference toFIG. 22, the valve 2126 may be controlled to allow a blast of air to bereleased through the outer lumens 2402 to clear the fluid or otherblockage from the outer lumens 2402, i.e., by pushing air and fluid backtowards the dressing 2102 and out of the outer lumens 2402.

Referring now to FIG. 22, a flowchart of a process 2500 for clearingblockages in the first tubing 2106 is shown, according to an exemplaryembodiment. At step 2502, a potential blockage of one or more outerlumens 2402 is determined. As one example, the control circuit 2132 maydetect a blockage based on pressure measurements from the sensor 2124.As another example, the control circuit 2132 assumes a potentialblockage exists after a predetermined time period, i.e., such that steps2504-2508 are triggered at a predetermined frequency.

At step 2504, the valve 2126 is opened to allow a blast of airtherethrough. For example, the control circuit 2132 may provide anon-zero voltage to the solenoid 2206 of the valve 2126. The controlcircuit 2132 may cause the valve 2126 to be held in the open positionfor an extended time period, i.e., longer than the periods shown in FIG.22 and discussed with reference thereto below. For example, in oneembodiment the non-zero voltage is provided for approximately 500milliseconds to hold the valve 126 open for approximately 500milliseconds. When the valve 2126 is held open, a blast of air may flowtherethrough at a high airflow rate due to the pressure differentialbetween the surrounding environment (ambient air) and the sealed space.This blast of air may flow into a blocked outer lumen 2402 and push anyblockage out of the first tubing 2106 towards the dressing 2106.Blockages in the outer lumens 2402 may thereby be periodically clearedto allow free airflow through the outer lumens 2402, for example toensure that the measurements of the pressure sensor 2124 accuratelyrepresent the pressure at the wound space 2120.

At step 2506, the solenoid valve 2508 is closed. For example, thecontrol circuit 2132 causes approximately zero voltage to be providedacross the solenoid 2206. Airflow from the environment to the sealedspace is prevented. The pneumatic pump 2122 may be operated toreestablish a desired negative pressure at the wound space 2120.

Referring now to FIG. 23, a flowchart of a process 2600 for wound volumedetermination and wound therapy customization is shown, according to anexemplary embodiment. The process 2600 may be carried out by the NPIWTsystem 100 of FIG. 18.

At step 2602, a sealed space defined by the wound 2114, the dressing2102, the first tubing 2106, and the canister 2104 is established. Thesealed space includes the wound space 2120. In other words, the dressing2102 is applied to the wound 2114 with the drape 2116 sealed over thewound 2114 and the foam layer 2118 (or other layers included in thedressing 2102 in various embodiments) to define the wound space 2120.The first tubing 2106 is coupled to the drape 2116 in fluidcommunication with the wound space 2120 via the connection pad 2121. Thefirst tubing 2106 is also coupled to the canister 2104 in fluidcommunication with the canister 2104.

At step 2604, the pneumatic pump 2122 is operated to draw a negativepressure in the sealed space. That is, the control circuit 2132 providesa control signal to the pneumatic pump 2122 that causes the pneumaticpump to remove air from the sealed space. The control circuit 2132 mayreceive pressure measurements from pressure sensor 2124 and cause thepneumatic pump 2122 to cease operation when a desired negative pressureis achieved (e.g., −125mmHg) and/or otherwise control the pneumatic pump2122 based on the pressure measurements to provide a desired negativepressure or pattern of desired negative pressures.

At step 2606, the valve 2126 is repeatedly opened and closed (e.g.,“cycled”) to allow a controlled rate of airflow therethrough. Thecontrol circuit 2132 may provide a control signal to the valve 2126 thatcauses the valve 2126 to repeatedly open and close. For example, in anembodiment where the valve 2126 is a solenoid valve, for example asshown in FIGS. 19-20, at step 2606 the control circuit 2132 provides avoltage pattern to the valve 2126. That is, the control circuit 2132 mayrepeatedly alternate a voltage differential across between the positivelead 2210 and the negative lead 2212 between approximately zero voltsand a non-zero voltage (e.g., approximately five volts). For example,the voltage pattern may include a step function that repeatedly stepsbetween approximately zero voltage and the non-zero voltage.

In one example, as shown in FIG. 24 and described in detail withreference thereto, the voltage pattern may include a repeating patternof approximately 400 milliseconds at the non-zero voltage, approximately100 milliseconds at approximately zero voltage, approximately 400milliseconds at the non-zero voltage, and approximately 100 millisecondsat approximately zero voltage. The voltage pattern may thereby cause thevalve 2126 to alternate between the open position and the closedposition with a period of approximately 500 milliseconds. In someembodiments, the voltage pattern may include a first set of tworepetitions of the repeating pattern, followed by approximately onesecond at approximately zero voltage, followed by a second set of tworepetitions of the repeating pattern. In preferred embodiments, thenon-zero voltage is provided, in each repetition, for no more than amaximum continuous duration of approximately 500 milliseconds.

By controlling the valve 2126 to repeatedly alternate between the openposition and the closed position, a controlled rate of airflow isallowed therethrough across the repetitions. That is, a lower rate ofairflow is allow through the valve 2126 as compared to holding the valve2126 open for an extended or indefinite amount of time (e.g., asdescribed for process 500), for example 500 milliseconds or longer. Thecontrolled rate may be customized by altering the voltage pattern.Additionally, the controlled rate may be known based on the voltagepattern. For example, the controlled rate may be predetermined by benchtesting for each of one or more voltage patterns. In preferredembodiments, the controlled rate is less than a restriction rate of thefilter 2138.

At step 608, the pressure in the sealed space is measured as thenegative pressure in the sealed space decays towards ambient pressure(i.e., approaches approximately atmospheric pressure). The controlledairflow through the valve 2126 allows air to enter the sealed space andcauses the pressure in the sealed space to decay towards ambientpressure. The sensor 2124 may measure the pressure in the sealed spaceand provide the pressure measurements to the control circuit 2132. Thecontrol circuit 2132 may record (store, save) the pressure measurements.In some embodiments, the control circuit 2132 may collect the pressuremeasurements to form a pressure decay curve.

At step 610, the volume of the wound space 2120 is determined based onthe pressure measurements. For example, based on the known controlledrate of airflow through the valve 2126 and the measured pressure decaycurve, the volume of the sealed space may be determined. The volume ofthe wound space may then be determined by removing a volume of thecanister and tube from the total volume of the sealed space. In somecases, one or more additional valves, sensors, etc. are included tofacilitate generation and collection of data for use in wound sizedetermination. Various methods for calculating wound size are possiblein various embodiments, for example as described with reference to FIGS.1-17.

At step 2612, the wound size (e.g., the volume of the wound space 2120)and/or a message relating thereto is displayed on the user interface2128. For example, the control circuit 2130 may cause a graphical userinterface that includes the wound size to be displayed on a screen ofthe user interface 2128. As another example, the control circuit 2130may determine one or more warnings, progress reports, or otherwound-related message based on the wound size and control the userinterface 2128 to display the warning, report, or other message. Forexample, the user interface 2128 may display a graphical representationof change in the volume of the wound space over time.

At step 2614, a wound therapy is customized based on the volume of thewound space. In some embodiments, the control circuit 2130 automaticallycustomizes a wound therapy based on the determined volume of the woundspace 2120. In other embodiments, a user is facilitated in customizing awound therapy based on the volume of the wound space 2120 based oninformation displayed on the user interface 2128.

In the example shown, the control circuit 2130 automatically customizesinstillation by automatically determining an amount of instillationfluid to be supplied to the wound space 2120 based on the determinedvolume of the wound space 2120. For example, the control circuit 2130may multiple the determined volume of the wound space 2120 by a scalingfactor to determine the amount of instillation fluid to be supplied tothe wound space 2120. As another example, the control circuit 2130 maydetermine the amount of instillation to be supplied as equal to thevolume of the wound space 2120. Various calculations are possible forvarious applications, wound types, instillation fluid types, patientand/or caregiver preferences, etc.

At step 2616, the customized wound therapy is provided. For example, thecontrol circuit 2130 may control the instillation pump 2130 to providethe determined amount of instillation fluid from the instillation fluidsource 2110 to the wound space 2120. Instillation therapy may thereby betailored to meet the needs of the healing wound in real time. Variousother customized therapies are possible in various embodiments.

Referring now to FIG. 24, a collection of graphs illustrating theoperation of the NPIWT system 2100 is shown, according to an exemplaryembodiment. FIG. 24 shows a measured pressure graph 2700, a controlsignal graph 2702, and an introduced pressure graph 2704. The pressuregraph 2700 illustrates a change in pressure in the sealed space overtime as measured by the pressure sensor 2124. As illustrated by thepressure graph 2700, a measured pressure line 2706 approaches a desirednegative pressure (shown as −200 mmHg) as the pneumatic pump 2122 isoperated to draw air out of the sealed space. The measured pressure thendecays as the valve 2126 is controlled to allow a controlled rate ofairflow therethrough.

The control signal graph 2702 illustrates a voltage pattern applied tothe valve 2126 (i.e., across the solenoid 2206). As shown, a controlsignal 2708 alternates between approximately zero voltage and a non-zerovoltage, shown as approximately five volts. As shown, the control signalincludes approximately 400 milliseconds at the non-zero voltage,approximately 100 milliseconds at approximately zero voltage, anotherapproximately 400 milliseconds at the non-zero voltage, and anotherapproximately 100 milliseconds at approximately zero voltage. Afterthese two repetitions (i.e., after two periods of 500 milliseconds), thecontrol signal may include one second at approximately zero voltage asillustrated in FIG. 24. It should be understood that various otherfrequencies and periods for a voltage pattern may be used in variousembodiments. As one possible additional example, in an alternativeembodiment the voltage pattern alternates between approximately 200milliseconds at a non-zero voltage and 50 milliseconds at approximatelyzero voltage for three or more repetitions (e.g., four repetitions),followed by approximately one second at approximately zero voltagebefore repeating the voltage pattern. In various embodiments, thenon-zero voltage is repeatedly provided for a duration between a minimumcontinuous duration of approximately 50 milliseconds and a maximumcontinuous duration of approximately 500 milliseconds, with alternatingperiods of approximately zero voltage.

The introduced pressure graph 2704 illustrates the amount of pressurelet into the sealed space over time. In the example shown, approximately5 mmHg is introduced into the sealed space for each 400 millisecondsegment of non-zero voltage in the control signal 708. The introducedpressure graph 2704 illustrates that the pressure decay in the sealedspace may be managed by the alternating pattern of the valve 2126 (i.e.,of the control signal 2708). For example, the introduced pressure graph2704 indicates that a lag time may exist between the beginning of anon-zero voltage period and a point in time corresponding to peak rateof pressure reduction or peak rate of airflow through the valve 2126.

Referring now to FIG. 8, the NPIWT system 2100 of FIG. 18 is shown in analternative embodiment. In the embodiment shown, the volume of thesealed space and/or the wound space can be determined by firstdetermining the restriction rate of the filter 2138 (i.e., the rate ofairflow through the filter 2138) as part of a calibration process beforetherapy is started. As shown in FIG. 18, a removable cap (structure,cover, joint) 2800 is placed proximate a point wherein the inner lumen2400 and the outer lumens 2402 come together to form the first tubing2106 (e.g., at a port of the canister 2104). For example, the firsttubing 2106 may be disconnected at this point and replaced by theremovable cap 2800 as shown in FIG. 8. The removable cap 2800 connectsthe inner lumen 2400 and the outer lumens 2402 and causes air to flowdirectly therebetween (i.e., without passing through the dressing 2102)during a process for determining the restriction rate of the filter2138. The removable cap 2800 may then be removed and the first tubing2106 connected in the configuration described above.

To determine the restriction rate of the filter 2138 while the removablecap 2800 is applied as in FIG. 8, the valve 2126 is closed and thepneumatic pump 2122 is run to remove air from the canister 2104. Thevalve 2126 may then be opened for an indefinite amount of time to allowair to flow back into the canister 2104 while the pressure sensor 2124measures the change in pressure over time. Based on a known volume ofthe canister 2104 and the change in pressure over time while the valve2126 is open, the control circuit 2132 may calculate the rate of airflowthrough the filter. The cap 2800 facilitates this process by ensuringthat the unknown volume of the wound space does not influence the rateof change of the pressure during such a process.

Configuration of Exemplary Embodiments

As utilized herein, the terms “approximately,” “about,” “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the disclosure as recited inthe appended claims.

It should be noted that the term “exemplary” and variations thereof, asused herein to describe various embodiments, are intended to indicatethat such embodiments are possible examples, representations, orillustrations of possible embodiments (and such terms are not intendedto connote that such embodiments are necessarily extraordinary orsuperlative examples).

The term “coupled” and variations thereof, as used herein, means thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent or fixed) or moveable (e.g.,removable or releasable). Such joining may be achieved with the twomembers coupled directly to each other, with the two members coupled toeach other using a separate intervening member and any additionalintermediate members coupled with one another, or with the two memberscoupled to each other using an intervening member that is integrallyformed as a single unitary body with one of the two members. If“coupled” or variations thereof are modified by an additional term(e.g., directly coupled), the generic definition of “coupled” providedabove is modified by the plain language meaning of the additional term(e.g., “directly coupled” means the joining of two members without anyseparate intervening member), resulting in a narrower definition thanthe generic definition of “coupled” provided above. Such coupling may bemechanical, electrical, or fluidic.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below”) are merely used to describe the orientation of variouselements in the FIGURES. It should be noted that the orientation ofvarious elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure. Although the figures show a specific order of method steps,the order of the steps may differ from what is depicted. Also two ormore steps can be performed concurrently or with partial concurrence.Such variation will depend on the software and hardware systems chosenand on designer choice. All such variations are within the scope of thedisclosure. Likewise, software implementations could be accomplishedwith standard programming techniques with rule based logic and otherlogic to accomplish the various connection steps, calculation steps,processing steps, comparison steps, and decision steps.

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.). For example, the position of elements can bereversed or otherwise varied and the nature or number of discreteelements or positions can be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure. The order or sequence of any process or method stepscan be varied or re-sequenced according to alternative embodiments.Other substitutions, modifications, changes, and omissions can be madein the design, operating conditions and arrangement of the exemplaryembodiments without departing from the scope of the present disclosure.

As used herein, the term “circuit” may include hardware structured toexecute the functions described herein. In some embodiments, eachrespective “circuit” may include machine-readable media for configuringthe hardware to execute the functions described herein. The circuit maybe embodied as one or more circuitry components including, but notlimited to, processing circuitry, network interfaces, peripheraldevices, input devices, output devices, sensors, etc. In someembodiments, a circuit may take the form of one or more analog circuits,electronic circuits (e.g., integrated circuits (IC), discrete circuits,system on a chip (SOCs) circuits, etc.), telecommunication circuits,hybrid circuits, and any other type of “circuit.” In this regard, the“circuit” may include any type of component for accomplishing orfacilitating achievement of the operations described herein. Forexample, a circuit as described herein may include one or moretransistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR,etc.), resistors, multiplexers, registers, capacitors, inductors,diodes, wiring, and so on).

The “circuit” may also include one or more processors communicablycoupled to one or more memory or memory devices. In this regard, the oneor more processors may execute instructions stored in the memory or mayexecute instructions otherwise accessible to the one or more processors.In some embodiments, the one or more processors may be embodied invarious ways. The one or more processors may be constructed in a mannersufficient to perform at least the operations described herein. In someembodiments, the one or more processors may be shared by multiplecircuits (e.g., circuit A and circuit B may comprise or otherwise sharethe same processor which, in some example embodiments, may executeinstructions stored, or otherwise accessed, via different areas ofmemory). Alternatively or additionally, the one or more processors maybe structured to perform or otherwise execute certain operationsindependent of one or more co-processors. In other example embodiments,two or more processors may be coupled via a bus to enable independent,parallel, pipelined, or multi-threaded instruction execution. Eachprocessor may be implemented as one or more general-purpose processors,application specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), digital signal processors (DSPs), or other suitableelectronic data processing components structured to execute instructionsprovided by memory. The one or more processors may take the form of asingle core processor, multi-core processor (e.g., a dual coreprocessor, triple core processor, quad core processor, etc.),microprocessor, etc. In some embodiments, the one or more processors maybe external to the apparatus, for example the one or more processors maybe a remote processor (e.g., a cloud based processor). Alternatively oradditionally, the one or more processors may be internal and/or local tothe apparatus. In this regard, a given circuit or components thereof maybe disposed locally (e.g., as part of a local server, a local computingsystem, etc.) or remotely (e.g., as part of a remote server such as acloud based server). To that end, a “circuit” as described herein mayinclude components that are distributed across one or more locations.The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure can be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Combinationsof the above are also included within the scope of machine-readablemedia. Machine-executable instructions include, for example,instructions and data which cause a general purpose computer, specialpurpose computer, or special purpose processing machines to perform acertain function or group of functions.

What is claimed is:
 1. A wound therapy system, comprising: a dressingsealable over a wound and defining a wound space between the dressingand the wound; tubing coupled to the dressing and fluidly communicablewith the wound space; a canister fluidly communicable with the tubing,wherein the canister, the tubing, and the dressing define a sealed spacecomprising the wound space; and a therapy unit coupled to the canisterand comprising: a pneumatic pump fluidly communicable with the sealedspace; a sensor configured to measure a pressure in the sealed space; avalve positioned between the sealed space and a surrounding environmentand controllable between an open position and a closed position; and acontrol circuit configured to: control the pneumatic pump to remove airfrom the sealed space to establish a negative pressure in the sealedspace; control the valve to repeatedly alternate between the openposition and the closed position to allow a controlled rate of airflowthrough the valve; receive measurements of the pressure in the sealedspace from the sensor; and determine a volume of the wound space basedon the measurements of the pressure.
 2. The wound therapy system ofclaim 1, wherein the controlled rate of airflow is less than arestriction rate of a filter positioned between the valve and thecanister.
 3. The wound therapy system of claim 1, wherein the valvecomprises a solenoid valve; and wherein the control circuit isconfigured to control the valve to repeatedly alternate between the openposition and the closed position by providing a voltage pattern to thesolenoid valve.
 4. The wound therapy system of claim 3, wherein thevoltage pattern comprises a step function repeatedly stepping betweenapproximately zero voltage and a non-zero voltage.
 5. The wound therapysystem of claim 4, wherein the voltage pattern remains at the non-zerovoltage for no more than a maximum continuous duration of approximately500 milliseconds.
 6. The wound therapy system of claim 5, whereinvoltage pattern comprises a repeating pattern of approximately 400milliseconds at a non-zero voltage, approximately 100 milliseconds atapproximately zero voltage, approximately 400 milliseconds at thenon-zero voltage, and approximately 100 milliseconds at approximatelyzero voltage.
 7. The wound therapy system of claim 6, wherein thevoltage pattern comprises a first set of two periods of the repeatingpattern, approximately one second at approximately zero voltage, and asecond set of two periods of the repeating pattern.
 8. The wound therapysystem of claim 3, wherein the voltage pattern causes the solenoid valveto alternate between the open position and the closed position with aperiod of approximately 500 milliseconds.
 9. The wound therapy system ofclaim 1, wherein the control circuit is further configured to: customizea customized wound therapy based on the volume of the wound space; andcontrol the therapy unit to provide the customized wound therapy. 10.The wound therapy system of claim 9, wherein the customized woundtherapy comprises instillation therapy.
 11. The wound therapy system ofclaim 10, wherein the control circuit is configured to customize theinstillation therapy by determining an amount of instillation fluid tosupply to the wound space based on the volume of the wound space. 12.The wound therapy system of claim 11, comprising: instillation tubingcoupled to the dressing and fluidly communicable with the wound space; asource of the instillation fluid fluidly communicable with theinstillation tubing; and an instillation pump controllable by thecontrol circuit to provide the amount of the instillation fluid from thesource to the wound space.
 13. A method of treating a wound, comprising:establishing a sealed space defined by a dressing, tubing, and acanister of a wound therapy system, the sealed space comprising a woundspace defined by the dressing and the wound; removing, with a pneumaticpump, air from the sealed space to establish a negative pressure in thesealed space; causing a solenoid valve to alternate between an openposition and a closed position, the solenoid valve allowing an airflowfrom a surrounding environment to the sealed space in the open positionand preventing the airflow from the surrounding environment to thesealed space in the closed position; measuring the pressure in thesealed space to generate pressure measurements; determining, based onthe pressure measurements, a volume of the wound space; customizing acustomized wound therapy based on the volume of the wound space; andproviding the customized wound therapy to the wound.
 14. The method ofclaim 13, wherein customizing a customized wound therapy comprisesdetermining an amount of an instillation fluid to be supplied to thewound space based on the volume of the wound space; and whereinproviding the customized wound therapy to the wound comprisescontrolling an instillation pump to supply the amount of theinstillation fluid to the wound space.
 15. The method of claim 13,wherein causing the solenoid valve to alternate between the openposition and the closed position provides a controlled rate of airflowfrom the surrounding environment to the sealed space.
 16. The method ofclaim 15, wherein the controlled rate of airflow is less than arestriction rate of a filter positioned between the canister and thesolenoid valve.
 17. The method of claim 13, wherein causing the solenoidvalve to alternate between the open position and the closed positioncomprises providing a voltage pattern to the solenoid valve.
 18. Themethod of claim 17, wherein the voltage pattern comprises a stepfunction repeatedly stepping between approximately zero voltage and anon-zero voltage.
 19. The method of claim 17, wherein voltage patterncomprises a repeating pattern of approximately 400 milliseconds at anon-zero voltage, approximately 100 milliseconds at approximately zerovoltage, approximately 400 milliseconds at the non-zero voltage, andapproximately 100 milliseconds at approximately zero voltage.
 20. Themethod of claim 19, wherein the voltage pattern comprises a first set oftwo periods of the repeating pattern, approximately one second atapproximately zero voltage, and a second set of two periods of therepeating pattern.
 21. The method of claim 19, wherein the non-zerovoltage causes the solenoid valve to be in the open position; andwherein a positive pressure of approximately 5 mmHg is provided to thesealed space during each 400 milliseconds at the non-zero voltage.
 22. Atherapy unit, comprising: a pneumatic pump fluidly communicable with asealed space; a sensor configured to measure a pressure in the sealedspace; a valve positioned between the sealed space and a surroundingenvironment and controllable between an open position and a closedposition; and a control circuit configured to: control the pneumaticpump to remove air from the sealed space to establish a negativepressure in the sealed space; control the valve to repeatedly alternatebetween the open position and the closed position to allow a controlledrate of airflow through the valve; receive measurements of the pressurein the sealed space from the sensor; and determine a volume of thesealed space based on the measurements of the pressure and thecontrolled rate.
 23. The therapy unit of claim 22, wherein the controlcircuit is configured to allow the controlled rate of airflow throughthe valve by controlling the valve to the open position for no longerthan a maximum continuous duration of approximately 500 milliseconds.24. A wound therapy system, comprising: a pneumatic pump fluidlycommunicable with a canister; tubing comprising a first lumen and asecond lumen, the first lumen configured to facilitate the flow of fluidfrom a dressing to the canister and the second lumen configured tofacilitate measurement of a pressure at the dressing; a sensorconfigured to measure a pressure in the second lumen; a valve positionedbetween a second lumen and a surrounding environment and controllablebetween an open position and a closed position; a filter positionedbetween the valve and the second lumen; and a cap removeably coupleableto the tubing, wherein the cap provides fluid communication between thefirst lumen and the second lumen when the cap is coupled to the tubing;a control circuit configured to, while the cap is coupled to the tubing,operate the pump to remove air from the canister, control the valve tothe open position, receive measurements of the pressure in the secondlumen from the sensor, and determine, based on the measurements of thepressure in the second lumen, a flow rate through the filter.
 25. Thewound therapy system of claim 24, wherein the control circuit isconfigured to, while the cap is removed from the tubing and the dressingis coupled to the tubing, determine a volume of a wound space based onthe flow rate through the filter and additional measurements of thepressure from the sensor.
 26. The wound therapy system of claim 24,wherein the control circuit is configured to provide a customized woundtherapy based on the volume of the wound space.